defconfig: 8994: Enable secure touch

Enable this feature in the drivers for the Atmel MXT and the
Synaptics controllers.
The feature is turned on/off at runtime via a sysfs file.

Change-Id: I0b23ba1e13522fb943cd3f0c1ab06f0fd4fb0a00
Acked-by: Christian Bolis <cbolis@qti.qualcomm.com>
Signed-off-by: Keith Fallows <keithf@codeaurora.org>