HID: Wacom Graphire Bluetooth driver

Based on the work by Andrew Zabolotny, an HID driver for the Bluetooth
Wacom tablet. This is required as it uses a slightly different
protocols from what's currently support by the drivers/input/wacom*
driver, and those only support USB.

A user-space patch is required to activate mode 2 of the Wacom tablet,
as hidp does not support hid_output_raw_report.

Signed-off-by: Bastien Nocera <hadess@hadess.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>