input: ab8500-ponkey: Create AB8500 domain IRQ mapping

Before we can use any domain allocated IRQ, we need to first create a
map between the Hardware IRQ (hwirq) and the Linux Virtual IRQ (virq).
We do this with a helper function provided by the AB8500 IRQ domain
controller called ab8500_irq_get_virq(). We need to do this for both
IRQs which the Power-On-Key driver uses; one for button press, the other
for button depress.

Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>