gpio: zx: Add ZTE zx296702 GPIO support

Add ZTE zx296702 GPIO controller support

Signed-off-by: Jun Nie <jun.nie@linaro.org>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index f82cd67..558b867 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -116,3 +116,4 @@
 obj-$(CONFIG_GPIO_XTENSA)	+= gpio-xtensa.o
 obj-$(CONFIG_GPIO_ZEVIO)	+= gpio-zevio.o
 obj-$(CONFIG_GPIO_ZYNQ)		+= gpio-zynq.o
+obj-$(CONFIG_GPIO_ZX)		+= gpio-zx.o