gpio: hlwd: Add basic IRQ support

This patch implements level-triggered IRQs in the Hollywood GPIO driver.
Edge triggered interrupts are not supported in this GPIO controller, so
I moved their emulation into a separate patch.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/Kconfig

@@ -258,6 +258,7 @@ config GPIO_HLWD
 	tristate "Nintendo Wii (Hollywood) GPIO"
 	depends on OF_GPIO
 	select GPIO_GENERIC
+	select GPIOLIB_IRQCHIP
 	help
 	  Select this to support the GPIO controller of the Nintendo Wii.