ARM: exynos_defconfig: Enable Atmel maXTouch support

Many Exynos based Chromebooks have an Atmel trackpad so enable
support for it by default will make easier for users.
Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

arch/arm/configs/exynos_defconfig

@@ -60,6 +60,7 @@ CONFIG_KEYBOARD_CROS_EC=y
 # CONFIG_MOUSE_PS2 is not set
 CONFIG_MOUSE_CYAPA=y
 CONFIG_INPUT_TOUCHSCREEN=y
+CONFIG_TOUCHSCREEN_ATMEL_MXT=y
 CONFIG_SERIAL_8250=y
 CONFIG_SERIAL_SAMSUNG=y
 CONFIG_SERIAL_SAMSUNG_CONSOLE=y