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

 drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/vega10_thermal.c:128: warning: Function parameter or member 'hwmgr' not described in 'vega10_fan_ctrl_set_static_mode'
 drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/vega10_thermal.c:128: warning: Function parameter or member 'mode' not described in 'vega10_fan_ctrl_set_static_mode'
 drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/vega10_thermal.c:157: warning: Function parameter or member 'hwmgr' not described in 'vega10_fan_ctrl_set_default_mode'
 drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/vega10_thermal.c:176: warning: Cannot understand  * @fn vega10_enable_fan_control_feature
 drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/vega10_thermal.c:252: warning: Function parameter or member 'hwmgr' not described in 'vega10_fan_ctrl_set_fan_speed_percent'
 drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/vega10_thermal.c:252: warning: Function parameter or member 'speed' not described in 'vega10_fan_ctrl_set_fan_speed_percent'
 drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/vega10_thermal.c:290: warning: Function parameter or member 'hwmgr' not described in 'vega10_fan_ctrl_reset_fan_speed_to_default'
 drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/vega10_thermal.c:307: warning: Function parameter or member 'hwmgr' not described in 'vega10_fan_ctrl_set_fan_speed_rpm'
 drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/vega10_thermal.c:307: warning: Function parameter or member 'speed' not described in 'vega10_fan_ctrl_set_fan_speed_rpm'
 drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/vega10_thermal.c:339: warning: Function parameter or member 'hwmgr' not described in 'vega10_thermal_get_temperature'
 drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/vega10_thermal.c:365: warning: Function parameter or member 'hwmgr' not described in 'vega10_thermal_set_temperature_range'
 drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/vega10_thermal.c:365: warning: Function parameter or member 'range' not described in 'vega10_thermal_set_temperature_range'
 drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/vega10_thermal.c:414: warning: Function parameter or member 'hwmgr' not described in 'vega10_thermal_initialize'
 drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/vega10_thermal.c:437: warning: Function parameter or member 'hwmgr' not described in 'vega10_thermal_enable_alert'
 drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/vega10_thermal.c:468: warning: Function parameter or member 'hwmgr' not described in 'vega10_thermal_disable_alert'
 drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/vega10_thermal.c:496: warning: Function parameter or member 'hwmgr' not described in 'vega10_thermal_stop_thermal_controller'
 drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/vega10_thermal.c:515: warning: Function parameter or member 'hwmgr' not described in 'vega10_thermal_setup_fan_table'
 drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/vega10_thermal.c:618: warning: Function parameter or member 'hwmgr' not described in 'vega10_thermal_start_smc_fan_control'

Cc: Evan Quan <evan.quan@amd.com>
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: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>