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>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Bug: 268174392
(cherry picked from commit b912ed13)
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Iacfd7a5db15c417fd1f02c85e414e3137e8729ec