HID: wacom: Initial driver for Wacom Intuos4 Wireless (Bluetooth)

This is very basic driver for Wacom Intuos4 Wireless tablet. It supports only
position, pressure and pen buttons. More features will be added in the future.

Signed-off-by: Przemo Firszt <przemo@firszt.eu>
Acked-by: Ping Cheng <pinglinux@gmail.com>
Reviewed-by: Chris Bagwell <chris@cnpbagwell.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>