HID: multitouch: fix protocol for Elo panels

The previous protocol was nearly working, but when several fingers were
present on the sensor, those that were not moving were not updated
in the next report, introducing a lot of releases.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
Conflicts:
	drivers/hid/hid-multitouch.c
Signed-off-by: Jiri Kosina <jkosina@suse.cz>