gpio: select IRQ_DOMAIN for gpiolib irqchip helpers

These helpers depend on the IRQ_DOMAIN so select it explicitly,
as it will not be present on all platforms such as Intel
desktops and laptops using Intel-MID.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --cc drivers/gpio/Kconfig
Simple merge