Input: atmel_mxt_ts - implement support for T100 touch object

Add support for the new T100 object which replaces the previous T9
multitouch touchscreen object in recent maXTouch devices. T100 provides
improved reporting with selectable auxiliary information, and a type field
for hover/stylus/glove reporting.

The hovering finger support was based on Chung-Yih's work in the ChromiumOS
downstream kernel:

https://chromium-review.googlesource.com/#/c/219280/Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Yufeng Shen <miletus@chromium.org>
[javier: Factor out T9 and T100 init functions and rework hover support]
Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>