Input: add support for Wacom W8001 penabled serial touchscreen

The Wacom W8001 sensor is a sensor device (uses electromagnetic
resonance) and it is interfaced via its serial microcontroller
to the host.

Signed-off-by: Jaya Kumar <jayakumar.lkml@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>