HID: wacom: Cleanup unsupported device_type for BAMBOO_PT

Not all Bamboo support both pen and touch. Make sure we deal with
pen only and touch only devices properly.

Signed-off-by: Ping Cheng <pingc@wacom.com>
Tested-By: Aaron Skomra <aaron.skomra@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>