mfd: tc3589x: Enforce device-tree only mode

All systems using the TC3589x multifunction expander uses
devicetree, so don't clutter the place with a lot of
and assume it is there.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index c1e2ca3..dc1aaa8 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -669,6 +669,7 @@
 config GPIO_TC3589X
 	bool "TC3589X GPIOs"
 	depends on MFD_TC3589X
+	depends on OF_GPIO
 	select GPIOLIB_IRQCHIP
 	help
 	  This enables support for the GPIOs found on the TC3589X