Input: wacom - add support for the Bamboo Touch trackpad

Add support for the Bamboo Touch trackpad, and make it work with
both the Synaptics X Driver and the Multitouch X Driver. The device
uses MT slots internally, so the choice of protocol is a given.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Acked-by: Ping Cheng <pingc@wacom.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>