irqchip: renesas-intc-irqpin: Add suspend-to-RAM wake up support

Set the ->irq_enable() and ->irq_disable() methods to NULL to enable
lazy disable of interrupts, and set IRQCHIP_MASK_ON_SUSPEND to tell the
core that only IRQs marked as wake-ups need to stay enabled during
suspend-to-RAM.

This makes wake-up by gpio-keys from suspend-to-RAM work on
r8a7740/Armadillo.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lkml.kernel.org/r/1408546172-22484-1-git-send-email-geert+renesas@glider.be


Signed-off-by: Jason Cooper <jason@lakedaemon.net>