ARM: imx_v6_v7_defconfig: Enable TOUCHSCREEN_ATMEL_MXT

Toradex iMX6/iMX7-based modules and boards support LCDs
with an MicroChip ATMXT1066T2 touchscreen controller.

This patch enables the TOUCHSCREEN_ATMEL_MXT which supports
MXT-series controllers, including the ATMXT1066T2.
Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/configs/imx_v6_v7_defconfig

@@ -179,6 +179,7 @@ CONFIG_MOUSE_PS2=m
 CONFIG_MOUSE_PS2_ELANTECH=y
 CONFIG_INPUT_TOUCHSCREEN=y
 CONFIG_TOUCHSCREEN_ADS7846=y
+CONFIG_TOUCHSCREEN_ATMEL_MXT=y
 CONFIG_TOUCHSCREEN_DA9052=y
 CONFIG_TOUCHSCREEN_EGALAX=y
 CONFIG_TOUCHSCREEN_GOODIX=y