batman-adv: check for more types of invalid IP addresses in DAT

There are more types of IP addresses that may appear in ARP packets that we
don't want to process. While some of these should never appear in sane ARP
packets, a 0.0.0.0 source is used for duplicate address detection and thus seen
quite often.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
Acked-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>