packet if the touchpad actually is a Dualpoint device.  The Glidepoint
modelsdon't have a stick, and can report z == 127 for a very wide finger.
If such a packet is parsed as a stick packet, the mouse pointer will
typically jump to one corner of the screen.
Signed-off-by: Peter Osterlund <petero2@telia.com>
Signed-off-by: Vojtech Pavlik <vojtech@suse.cz>