gpio/qoriq: select IRQ_DOMAIN

The gpio-mpc8xxx driver requires IRQ domains but can be built
without them, resulting on a failure to build certain randconfigs
on ARM:

drivers/gpio/gpio-mpc8xxx.c: In function 'mpc8xxx_gpio_to_irq':
drivers/gpio/gpio-mpc8xxx.c:92:10: error: implicit declaration of function 'irq_create_mapping' [-Werror=implicit-function-declaration]
   return irq_create_mapping(mpc8xxx_gc->irq, offset);

This selects IRQ_DOMAIN from the driver to ensure we can build it.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 5df7fd46 ("gpio/qoriq: Add qoriq platforms support")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/Kconfig

@@ -303,6 +303,7 @@ config GPIO_MPC8XXX
 		   FSL_SOC_BOOKE || PPC_86xx || ARCH_LAYERSCAPE || ARM || \
 		   COMPILE_TEST
 	select GPIO_GENERIC
+	select IRQ_DOMAIN
 	help
 	  Say Y here if you're going to use hardware that connects to the
 	  MPC512x/831x/834x/837x/8572/8610/QorIQ GPIOs.