io-wq: use __set_notify_signal() to wake workers

io-wq: use __set_notify_signal() to wake workers

The only difference between set_notify_signal() and __set_notify_signal()
is that the former checks if it needs to deliver an IPI to force a
reschedule. As the io-wq workers never leave the kernel, and IPI is never
needed, they simply need a wakeup.

Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/20220426014904.60384-4-axboe@kernel.dk
Signed-off-by: Jens Axboe <axboe@kernel.dk>