drm/ttm: drop the spin in delayed delete if the trylock doesn't work

Thomas actually noticed that, but I didn't realized what he meant until
now.
Signed-off-by: NChristian König <christian.koenig@amd.com>
Reviewed-by: NRoger He <Hongbo.He@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/ttm/ttm_bo.c

@@ -592,6 +592,8 @@ static bool ttm_bo_delayed_delete(struct ttm_bo_device *bdev, bool remove_all)
 
 		} else if (reservation_object_trylock(bo->resv)) {
 			ttm_bo_cleanup_refs(bo, false, !remove_all, true);
+		} else {
+			spin_unlock(&glob->lru_lock);
 		}
 
 		kref_put(&bo->list_kref, ttm_bo_release_list);