UPSTREAM: io_uring: move common poll bits

[ upstream commmit 5641897a ]

Move some poll helpers/etc up, we'll need them there shortly

Change-Id: Ibd4af25105c3340c3ad69038f65e95b72a538676
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6c5c3dba24c86aad5cd389a54a8c7412e6a0621d.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 a85d7ac1)
Bug: 268174392
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>