gpio: zx: depend on ARCH_ZX

Set GPIO_ZX to depend on ARCH_ZX as it's SOC specific.

Signed-off-by: Peter Robinson <pbrobinson@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index b19e847..3d39ff7 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -524,6 +524,7 @@
 
 config GPIO_ZX
 	bool "ZTE ZX GPIO support"
+	depends on ARCH_ZX || COMPILE_TEST
 	select GPIOLIB_IRQCHIP
 	help
 	  Say yes here to support the GPIO device on ZTE ZX SoCs.