gpio: Add STMPE GPIO driver

Add support for the GPIOs on STMPE I/O Expanders.

[l.fu@pengutronix.de: fix set direction input]
[l.fu@pengutronix.de: set GPIO alternate function while requesting]
Acked-by: Luotao Fu <l.fu@pengutronix.de>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index a69e060..fc6019d 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -20,6 +20,7 @@
 obj-$(CONFIG_GPIO_PCA953X)	+= pca953x.o
 obj-$(CONFIG_GPIO_PCF857X)	+= pcf857x.o
 obj-$(CONFIG_GPIO_PL061)	+= pl061.o
+obj-$(CONFIG_GPIO_STMPE)	+= stmpe-gpio.o
 obj-$(CONFIG_GPIO_TC35892)	+= tc35892-gpio.o
 obj-$(CONFIG_GPIO_TIMBERDALE)	+= timbgpio.o
 obj-$(CONFIG_GPIO_TWL4030)	+= twl4030-gpio.o