Speedlink VAD Cezanne have a hardware bug that makes the cursor "jump" from one
place to another every now and then. The issue are relative motion events
erroneously reported by the device, each having a distance value of +256. This
256 can in fact never occur due to real motion, therefore those events can
safely be ignored.  The driver also drops useless EV_REL events with a value of
0, that the device sends every time it sends an "real" EV_REL or EV_KEY event.
Signed-off-by: NStefan Kriwanek <mail@stefankriwanek.de>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>