HID: hid-multitouch: cosmetic changes, sort classes and devices

This patch sorts the defs for the MT_CLS. I choose to split
generic classes and device specific ones to be able to add
more generic classes in the future.

It also put eGalax devices at their right place (alphabetically)
in mt_devices.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@enac.fr>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>