Input: add driver for Maxim max11801 touchscreen controller

Add MAXI max11801 resistive touchscreen controller driver. This driver
uses Auto Mode and Aperture Mode.

Support for other max1180x devices can be added to this driver as well,
as they use almost the same register addresses and codes.

You can find data sheet here:
http://www.maxim-ic.com/datasheet/index.mvp/id/5943

Signed-off-by: Zhang Jiejing <jiejing.zhang@freescale.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>