gpio: omap: convert driver to use gpiolib irqchip

Converts the GPIO OMAP driver to register its chained irq
handler and irqchip using the helpers in the gpiolib core.

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 43a65ed..c58b828 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -247,6 +247,7 @@
 	bool "TI OMAP GPIO support"
 	default y if ARCH_OMAP
 	depends on ARM && ARCH_OMAP
+	select GPIOLIB_IRQCHIP
 	help
 	  Say yes here to enable GPIO support for TI OMAP SoCs.