io_uring: add timeout completion_lock annotation

Add one more sparse locking annotation for readability in
io_kill_timeout().
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/bdbb22026024eac29203c1aa0045c4954a2488d1.1618278933.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -1267,6 +1267,7 @@ static void io_queue_async_work(struct io_kiocb *req)
 }
 
 static void io_kill_timeout(struct io_kiocb *req, int status)
+	__must_hold(&req->ctx->completion_lock)
 {
 	struct io_timeout_data *io = req->async_data;
 	int ret;