ebtables-filter-mcast: drop ARPs to/from 0.0.0.0

Fixes https://github.com/freifunk-gluon/gluon/issues/311

package/gluon-ebtables-filter-multicast/files/lib/gluon/ebtables/110-mcast-allow-arp

@@ -1 +1,3 @@
+rule 'MULTICAST_OUT -p ARP --arp-opcode Reply --arp-ip-src 0.0.0.0 -j DROP'
+rule 'MULTICAST_OUT -p ARP --arp-opcode Request --arp-ip-dst 0.0.0.0 -j DROP'
 rule 'MULTICAST_OUT -p ARP -j RETURN'