gpio-ml-ioh: Support interrupt function

Signed-off-by: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index d539efd..04499c1 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -402,6 +402,7 @@
 config GPIO_ML_IOH
 	tristate "OKI SEMICONDUCTOR ML7213 IOH GPIO support"
 	depends on PCI
+	select GENERIC_IRQ_CHIP
 	help
 	  ML7213 is companion chip for Intel Atom E6xx series.
 	  This driver can be used for OKI SEMICONDUCTOR ML7213 IOH(Input/Output