Input: add mc13783 touchscreen driver

This driver provides support for the touchscreen interface
integrated into the Freescale MC13783.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Luotao Fu <l.fu@pengutronix.de>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>