ARM: exynos_defconfig: compile Atmel MXT touchscreeen as module

The Atmel MXT touchscreen can load firmware and settings from the
/lib/firmware directory, it makes sense to have it as a module to have
more control over the loading process.
Signed-off-by: Martin Jücker <martin.juecker@gmail.com>
Link: https://lore.kernel.org/r/20201113212525.13455-5-martin.juecker@gmail.comSigned-off-by: Krzysztof Kozlowski <krzk@kernel.org>

arch/arm/configs/exynos_defconfig

@@ -127,7 +127,7 @@ 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_TOUCHSCREEN_ATMEL_MXT=m
 CONFIG_TOUCHSCREEN_MMS114=y
 CONFIG_INPUT_MISC=y
 CONFIG_INPUT_MAX77693_HAPTIC=y