pinctrl: coh901: convert driver to use gpiolib irqchip

This converts the COH901 pin control driver to register its
chained irq handler and irqchip using the helpers in the
gpiolib core.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/Kconfig

@@ -324,6 +324,7 @@ config PINCTRL_U300
 config PINCTRL_COH901
 	bool "ST-Ericsson U300 COH 901 335/571 GPIO"
 	depends on GPIOLIB && ARCH_U300 && PINCTRL_U300
+	select GPIOLIB_IRQCHIP
 	help
 	  Say yes here to support GPIO interface on ST-Ericsson U300.
 	  The names of the two IP block variants supported are