gpio: add tps65218 gpio

Driver for the GPIO block found in ti's tps65218 pmics.

The device has two GPIOs and one GPO pin which can be configured as follows:
GPIO1:
	-general-purpose, open-drain output controlled by GPO1 user bit and/or
	 sequencer
	-DDR3 reset input signal from SOC. Signal is either latched or
	 passed-trough to GPO2 pin. See below for details.
GPO2:
	-general-purpose output controlled by GPO2 user bit
	-DDR3 reset output signal. Signal is controlled by GPIO1 and PGOOD.
	 See below for details.
	-Output buffer can be configured as open-drain or push-pull.
GPIO3:
	-general-purpose, open-drain output controlled by GPO3 user bit and/or
	 sequencer
	-reset input-signal for DCDC1 and DCDC2.

The input configurations are not meant to be used by the user so the driver
only offers GPOs.

v2: Added request routine that evaluates the fw config flags and removed module
    owner
v3: Added .direction_input() routine, and took care of all Linus Walleij
suggestions (clamp to bool, use proper include)

Signed-off-by: Nicolas Saenz Julienne <nicolassaenzj@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 8d49603..f1d3d82 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -98,6 +98,7 @@
 obj-$(CONFIG_GPIO_TIMBERDALE)	+= gpio-timberdale.o
 obj-$(CONFIG_GPIO_PALMAS)	+= gpio-palmas.o
 obj-$(CONFIG_GPIO_TPIC2810)	+= gpio-tpic2810.o
+obj-$(CONFIG_GPIO_TPS65218)	+= gpio-tps65218.o
 obj-$(CONFIG_GPIO_TPS6586X)	+= gpio-tps6586x.o
 obj-$(CONFIG_GPIO_TPS65910)	+= gpio-tps65910.o
 obj-$(CONFIG_GPIO_TPS65912)	+= gpio-tps65912.o