Input: wacom - use hid communication instead of plain usb

Wacom.ko was a plain USB driver for a HID device. The communications
from/to the devices can actually be replaced with the HID API.

At the USB level, the reports are exactly the same.

This will allow to use uhid virtual devices instead of true USB devices.
This step is necessary to implement regression tests.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Reviewed-by: Jason Gerecke <killertofu@gmail.com>
Tested-by: Jason Gerecke <killertofu@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>