batman-adv: reorder packet types

Reordering the packet type numbers allows us to handle unicast
packets in a general way - even if we don't know the specific packet
type, we can still forward it. There was already code handling
this for a couple of unicast packets, and this is the more
generalized version to do that.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>