io_uring/net: use right helpers for async_data

There is another spot where we check ->async_data directly instead of
using req_has_async_data(), which is the way to do it, fix it up.

Fixes: 43e0bbbd0b ("io_uring: add netmsg cache")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/42f33b9a81dd6ae65dda92f0372b0ff82d548517.1660822636.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/net.c

@@ -152,9 +152,9 @@ static int io_setup_async_msg(struct io_kiocb *req,
 			      struct io_async_msghdr *kmsg,
 			      unsigned int issue_flags)
 {
-	struct io_async_msghdr *async_msg = req->async_data;
+	struct io_async_msghdr *async_msg;
 
-	if (async_msg)
+	if (req_has_async_data(req))
 		return -EAGAIN;
 	async_msg = io_recvmsg_alloc_async(req, issue_flags);
 	if (!async_msg) {