Input: atmel_mxt_ts - remove unnecessary platform data

It is not necessary to download these values to the maXTouch chip on every
probe, since they are stored in NVRAM. It makes life difficult when tuning
the device to keep them in sync with the config array/file, and requires a
new kernel build for minor tweaks.

These parameters only represent a tiny subset of the available
configuration options, tracking all of these options in platform data would
be a endless task. In addition, different versions of maXTouch chips may
have these values in different places or may not even have them at all.

Having these values also makes life more complex for device tree and other
platforms where having to define a static configuration isn't helpful.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Benson Leung <bleung@chromium.org>
Acked-by: Yufeng Shen <miletus@chromium.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>