Fixes the following W=1 kernel build warning(s):

 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:464: warning: Function parameter or member 'bo' not described in 'amdgpu_move_blit'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:464: warning: Function parameter or member 'evict' not described in 'amdgpu_move_blit'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:464: warning: Function parameter or member 'new_mem' not described in 'amdgpu_move_blit'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:464: warning: Function parameter or member 'old_mem' not described in 'amdgpu_move_blit'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:522: warning: Function parameter or member 'adev' not described in 'amdgpu_mem_visible'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:522: warning: Function parameter or member 'mem' not described in 'amdgpu_mem_visible'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:548: warning: Function parameter or member 'bo' not described in 'amdgpu_bo_move'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:548: warning: Function parameter or member 'evict' not described in 'amdgpu_bo_move'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:548: warning: Function parameter or member 'ctx' not described in 'amdgpu_bo_move'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:548: warning: Function parameter or member 'new_mem' not described in 'amdgpu_bo_move'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:548: warning: Function parameter or member 'hop' not described in 'amdgpu_bo_move'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:658: warning: Function parameter or member 'bdev' not described in 'amdgpu_ttm_io_mem_reserve'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:658: warning: Function parameter or member 'mem' not described in 'amdgpu_ttm_io_mem_reserve'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:751: warning: Function parameter or member 'bo' not described in 'amdgpu_ttm_tt_get_user_pages'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:751: warning: Function parameter or member 'pages' not described in 'amdgpu_ttm_tt_get_user_pages'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:855: warning: Function parameter or member 'ttm' not described in 'amdgpu_ttm_tt_get_user_pages_done'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:892: warning: Function parameter or member 'ttm' not described in 'amdgpu_ttm_tt_set_user_pages'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:892: warning: Function parameter or member 'pages' not described in 'amdgpu_ttm_tt_set_user_pages'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:906: warning: Function parameter or member 'bdev' not described in 'amdgpu_ttm_tt_pin_userptr'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:906: warning: Function parameter or member 'ttm' not described in 'amdgpu_ttm_tt_pin_userptr'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:944: warning: Function parameter or member 'bdev' not described in 'amdgpu_ttm_tt_unpin_userptr'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:944: warning: Function parameter or member 'ttm' not described in 'amdgpu_ttm_tt_unpin_userptr'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1029: warning: Function parameter or member 'bdev' not described in 'amdgpu_ttm_backend_bind'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1029: warning: Function parameter or member 'ttm' not described in 'amdgpu_ttm_backend_bind'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1029: warning: Function parameter or member 'bo_mem' not described in 'amdgpu_ttm_backend_bind'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1087: warning: Function parameter or member 'bo' not described in 'amdgpu_ttm_alloc_gart'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1146: warning: Function parameter or member 'tbo' not described in 'amdgpu_ttm_recover_gart'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1168: warning: Function parameter or member 'bdev' not described in 'amdgpu_ttm_backend_unbind'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1168: warning: Function parameter or member 'ttm' not described in 'amdgpu_ttm_backend_unbind'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1214: warning: Function parameter or member 'page_flags' not described in 'amdgpu_ttm_tt_create'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1247: warning: Function parameter or member 'bdev' not described in 'amdgpu_ttm_tt_populate'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1247: warning: Function parameter or member 'ttm' not described in 'amdgpu_ttm_tt_populate'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1247: warning: Function parameter or member 'ctx' not described in 'amdgpu_ttm_tt_populate'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1291: warning: Function parameter or member 'bdev' not described in 'amdgpu_ttm_tt_unpopulate'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1291: warning: Function parameter or member 'ttm' not described in 'amdgpu_ttm_tt_unpopulate'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1357: warning: Function parameter or member 'ttm' not described in 'amdgpu_ttm_tt_get_usermm'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1376: warning: Function parameter or member 'ttm' not described in 'amdgpu_ttm_tt_affect_userptr'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1376: warning: Function parameter or member 'start' not described in 'amdgpu_ttm_tt_affect_userptr'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1376: warning: Function parameter or member 'end' not described in 'amdgpu_ttm_tt_affect_userptr'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1397: warning: Function parameter or member 'ttm' not described in 'amdgpu_ttm_tt_is_userptr'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1410: warning: Function parameter or member 'ttm' not described in 'amdgpu_ttm_tt_is_readonly'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1449: warning: bad line:
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1454: warning: Function parameter or member 'adev' not described in 'amdgpu_ttm_tt_pte_flags'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1477: warning: Function parameter or member 'bo' not described in 'amdgpu_ttm_bo_eviction_valuable'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1477: warning: Function parameter or member 'place' not described in 'amdgpu_ttm_bo_eviction_valuable'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1787: warning: Function parameter or member 'adev' not described in 'amdgpu_ttm_init'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1915: warning: Function parameter or member 'adev' not described in 'amdgpu_ttm_late_init'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:1926: warning: Function parameter or member 'adev' not described in 'amdgpu_ttm_fini'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2250: warning: Function parameter or member 'f' not described in 'amdgpu_ttm_vram_read'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2250: warning: Function parameter or member 'buf' not described in 'amdgpu_ttm_vram_read'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2250: warning: Function parameter or member 'size' not described in 'amdgpu_ttm_vram_read'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2250: warning: Function parameter or member 'pos' not described in 'amdgpu_ttm_vram_read'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2285: warning: Function parameter or member 'f' not described in 'amdgpu_ttm_vram_write'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2285: warning: Function parameter or member 'buf' not described in 'amdgpu_ttm_vram_write'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2285: warning: Function parameter or member 'size' not described in 'amdgpu_ttm_vram_write'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2285: warning: Function parameter or member 'pos' not described in 'amdgpu_ttm_vram_write'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2336: warning: Function parameter or member 'f' not described in 'amdgpu_ttm_gtt_read'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2336: warning: Function parameter or member 'buf' not described in 'amdgpu_ttm_gtt_read'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2336: warning: Function parameter or member 'size' not described in 'amdgpu_ttm_gtt_read'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2336: warning: Function parameter or member 'pos' not described in 'amdgpu_ttm_gtt_read'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2390: warning: Function parameter or member 'f' not described in 'amdgpu_iomem_read'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2390: warning: Function parameter or member 'buf' not described in 'amdgpu_iomem_read'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2390: warning: Function parameter or member 'size' not described in 'amdgpu_iomem_read'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2390: warning: Function parameter or member 'pos' not described in 'amdgpu_iomem_read'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2446: warning: Function parameter or member 'f' not described in 'amdgpu_iomem_write'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2446: warning: Function parameter or member 'buf' not described in 'amdgpu_iomem_write'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2446: warning: Function parameter or member 'size' not described in 'amdgpu_iomem_write'
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:2446: warning: Function parameter or member 'pos' not described in 'amdgpu_iomem_write'

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Jerome Glisse <glisse@freedesktop.org>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>