drm/ttm: remove set but not used variable 'rdev'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/gpu/drm/radeon/radeon_ttm.c: In function 'radeon_move_vram_ram':
drivers/gpu/drm/radeon/radeon_ttm.c:254:24: warning:
 variable 'rdev' set but not used [-Wunused-but-set-variable]

drivers/gpu/drm/radeon/radeon_ttm.c: In function 'radeon_move_ram_vram':
drivers/gpu/drm/radeon/radeon_ttm.c:301:24: warning:
 variable 'rdev' set but not used [-Wunused-but-set-variable]

It's not used since a987fcaa ("ttm: Make parts of a struct ttm_bo_device
global.")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_ttm.c

@@ -251,14 +251,12 @@ static int radeon_move_vram_ram(struct ttm_buffer_object *bo,
 				struct ttm_mem_reg *new_mem)
 {
 	struct ttm_operation_ctx ctx = { interruptible, no_wait_gpu };
-	struct radeon_device *rdev;
 	struct ttm_mem_reg *old_mem = &bo->mem;
 	struct ttm_mem_reg tmp_mem;
 	struct ttm_place placements;
 	struct ttm_placement placement;
 	int r;
 
-	rdev = radeon_get_rdev(bo->bdev);
 	tmp_mem = *new_mem;
 	tmp_mem.mm_node = NULL;
 	placement.num_placement = 1;
@@ -298,14 +296,12 @@ static int radeon_move_ram_vram(struct ttm_buffer_object *bo,
 				struct ttm_mem_reg *new_mem)
 {
 	struct ttm_operation_ctx ctx = { interruptible, no_wait_gpu };
-	struct radeon_device *rdev;
 	struct ttm_mem_reg *old_mem = &bo->mem;
 	struct ttm_mem_reg tmp_mem;
 	struct ttm_placement placement;
 	struct ttm_place placements;
 	int r;
 
-	rdev = radeon_get_rdev(bo->bdev);
 	tmp_mem = *new_mem;
 	tmp_mem.mm_node = NULL;
 	placement.num_placement = 1;