UPSTREAM: io_uring: refactor poll update

[ upstream commmit 2bbb146d ]

Clean up io_poll_update() and unify cancellation paths for remove and
update.

Change-Id: I2c724364be99f1a8db026681c524ebfc5a71ee38
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/5937138b6265a1285220e2fab1b28132c1d73ce3.1639605189.git.asml.silence@gmail.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>
[pavel: backport]
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 040e58f5)
Bug: 268174392
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>