aio: Fix an error code in __io_submit_one()

This accidentally returns the wrong variable.  The "req->ki_eventfd"
pointer is NULL so this return success.

Fixes: 7316b49c ("aio: move sanity checks and request allocation to io_submit_one()")
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

fs/aio.c

@@ -1794,7 +1794,7 @@ static int __io_submit_one(struct kioctx *ctx, const struct iocb *iocb,
 		 */
 		eventfd = eventfd_ctx_fdget(iocb->aio_resfd);
 		if (IS_ERR(eventfd))
-			return PTR_ERR(req->ki_eventfd);
+			return PTR_ERR(eventfd);
 
 		req->ki_eventfd = eventfd;
 	}