io_uring: reuse io_should_terminate_tw() for cmds

io_uring_cmd_work() rolled a hard coded version of
io_should_terminate_tw() to avoid conflicts, but now it's time to
converge them.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/8a88dd6e4ed8e6c00c6552af0c20c9de02e458de.1736955455.git.asml.silence@gmail.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>