Input: add driver for Atmel AT42QT2160 Sensor Chip

This version only supports individual cells (no slide support yet).
The code has been tested on proprietary development ARM board, but
should work fine on other machines.

Signed-off-by: Raphael Derosso Pereira <raphaelpereira@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>