drm/amdgpu:fix memleak in takedown

this can fix the memory leak under the case that not all
BO are freed during "takedown" stage, because originally
it blocks following kfree on mgr.
Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c

@@ -71,12 +71,6 @@ static int amdgpu_gtt_mgr_fini(struct ttm_mem_type_manager *man)
 {
 	struct amdgpu_gtt_mgr *mgr = man->priv;
 
-	spin_lock(&mgr->lock);
-	if (!drm_mm_clean(&mgr->mm)) {
-		spin_unlock(&mgr->lock);
-		return -EBUSY;
-	}
-
 	drm_mm_takedown(&mgr->mm);
 	spin_unlock(&mgr->lock);
 	kfree(mgr);

drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c

@@ -68,11 +68,6 @@ static int amdgpu_vram_mgr_fini(struct ttm_mem_type_manager *man)
 	struct amdgpu_vram_mgr *mgr = man->priv;
 
 	spin_lock(&mgr->lock);
-	if (!drm_mm_clean(&mgr->mm)) {
-		spin_unlock(&mgr->lock);
-		return -EBUSY;
-	}
-
 	drm_mm_takedown(&mgr->mm);
 	spin_unlock(&mgr->lock);
 	kfree(mgr);