input: touchscreen: mxs-lradc: Add support for touchscreen

Add 4-wire/5-wire touchscreen controller.

Signed-off-by: Ksenija Stanojevic <ksenija.stanojevic@gmail.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>