Avoid requiring that a data being unregistered has to be initialized

src/datawizard/interfaces/data_interface.c

@@ -960,7 +960,7 @@ void starpu_data_unregister_submit(starpu_data_handle_t handle)
 	}
 
 	/* Wait for all task dependencies on this handle before putting it for free */
-	starpu_data_acquire_on_node_cb(handle, STARPU_ACQUIRE_NO_NODE_LOCK_ALL, STARPU_RW, _starpu_data_unregister_submit_cb, handle);
+	starpu_data_acquire_on_node_cb(handle, STARPU_ACQUIRE_NO_NODE_LOCK_ALL, STARPU_W, _starpu_data_unregister_submit_cb, handle);
 }
 
 static void _starpu_data_invalidate(void *data)