On some Intel BXT platform, wake-up from suspend-to-idle on pressing
power-button is not working. Its noticed that gpio-keys driver marking the
second level IRQ/power-button as wake capable but Intel pintctrl
driver is missing to mark GPIO chip/controller IRQ which first level IRQ
as wake cable if its GPIO pin IRQ is wakeble. So, though the first level
IRQ gets generated on power-button press, since it is not marked as
wake capable resume/wake-up flow is not happening.
Intel pintctrl/GPIO driver need to mark GPIO chip/controller IRQ (first
level IRQ) as wake capable iff GPIO pin's IRQ (second level IRQ) is marked
as wake cable.

Changes in v2:
 - Add missing irq initialisation.
Signed-off-by: Nilesh Bacchewar <nilesh.bacchewar@intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>