Input: wacom - move the USB (now hid) Wacom driver in drivers/hid

wacom.ko is now a full HID driver, we have to move it into the proper
subdirectory: drivers/hid.

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