drm/prime: double lock typo

There is a typo so deadlocks on error instead of unlocking.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@gmail.com>

drivers/gpu/drm/drm_prime.c

@@ -552,7 +552,7 @@ int drm_gem_prime_fd_to_handle(struct drm_device *dev,
 	 */
 	drm_gem_handle_delete(file_priv, *handle);
 out_unlock:
-	mutex_lock(&dev->object_name_lock);
+	mutex_unlock(&dev->object_name_lock);
 out_put:
 	dma_buf_put(dma_buf);
 	mutex_unlock(&file_priv->prime.lock);