HID: wacom: generic: add vendor defined touch

Add vendor defined touch to support the second generation Intuos Pro.
Previously all generic Wacom devices used true HID to report their touch.

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