Input: add driver for EETI touchpanels

This patch adds a driver for EETI's I2C connected touchscreens.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Tested-by: Sven Neumann <s.neumann@raumfeld.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>