io_uring: kill io_poll_issue's PF_EXITING check

We don't need to worry about checking PF_EXITING in io_poll_issue().
task works using the function should take care of it and never try to
resubmit / retry if the task is dying.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/2e9dc998dc07507c759a0c9cb5d2fbea0710d58c.1669821213.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/io_uring.c

@@ -1808,8 +1808,6 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
 int io_poll_issue(struct io_kiocb *req, bool *locked)
 {
 	io_tw_lock(req->ctx, locked);
-	if (unlikely(req->task->flags & PF_EXITING))
-		return -EFAULT;
 	return io_issue_sqe(req, IO_URING_F_NONBLOCK|IO_URING_F_MULTISHOT|
 				 IO_URING_F_COMPLETE_DEFER);
 }