Dealing with input, timing is important; if the button should be
released in one millisecond, then it should be done in one millisecond
and not a hundred milliseconds.

Therefore, the standard timer API is not really suitable for this task.

Convert the gpio-keys driver to use a hrtimer instead of the standard
timer to address this issue.

Note that by using a hard IRQ for the hrtimer callback, we can get rid
of the spin_lock_irqsave() and spin_unlock_irqrestore().
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20210307222240.380583-2-paul@crapouillou.netSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>