mfd: Kconfig: MFD_SUN4I_GPADC depends on !TOUCHSCREN_SUN4I_GPADC

MFD_SUN4I_GPADC and TOUCHSCREEN_SUN4I are incompatible (both are drivers
for Allwinner SoCs' ADC). This makes sure TOUCHSCREEN_SUN4I isn't
enabled while MFD_SUN4I_GPADC is enabled.
Signed-off-by: Quentin Schulz <quentin.schulz@free-electrons.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/Kconfig

@@ -46,6 +46,7 @@ config MFD_SUN4I_GPADC
 	select REGMAP_MMIO
 	select REGMAP_IRQ
 	depends on ARCH_SUNXI || COMPILE_TEST
+	depends on !TOUCHSCREEN_SUN4I
 	help
 	  Select this to get support for Allwinner SoCs (A10, A13 and A31) ADC.
 	  This driver will only map the hardware interrupt and registers, you