Input: lm8323 - use oneshot level triggered interrupts

According to the data sheet the interrupt should be level rather than
edge triggered.  This fixes the issue of the Nokia N810 keypad stopping
responding if multiple key events occur in quick succession.

Signed-off-by: Leigh Brown <leigh@solinno.co.uk>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>