Input: atmel_mxt_ts - allow board code to suppliy controller config

As there is no common configuration settings that would work in every
situation, remove the fixed config data from driver code and add
config data to platform data.

Signed-off-by: Iiro Valkonen <iiro.valkonen@atmel.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>