Counting number of touching fingers by wacom_wac_finger_count_touches so we
don't have to count them inside individual routines.
Signed-off-by: NPing Cheng <pingc@wacom.com>
Reviewed-by: NJason Gerecke <jason.gerecke@wacom.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>