io_uring: perform IOPOLL reaping if canceler is thread itself

io_uring: perform IOPOLL reaping if canceler is thread itself

BugLink: https://bugs.launchpad.net/bugs/1919492
[ Upstream commit d052d1d685f5125249ab4ff887562c88ba959638 ]

We bypass IOPOLL completion polling (and reaping) for the SQPOLL thread,
but if it's the thread itself invoking cancelations, then we still need
to perform it or no one will.

Fixes: 9936c7c2bc76 ("io_uring: deduplicate core cancellations sequence")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>