UPSTREAM: io_uring/io-wq: free worker if task_work creation is canceled

commit af82425c upstream.

If we cancel the task_work, the worker will never come into existance.
As this is the last reference to it, ensure that we get it freed
appropriately.

Cc: stable@vger.kernel.org
Reported-by: 진호 <wnwlsgh98@gmail.com>
Change-Id: I7da78f771d0845c98044a1181ea948c2784f1008
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit bb135bcc)
Bug: 268174392
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>