kernel: netfilter: xtables: avoid NFPROTO_UNSPEC where needed

In the Linux kernel, the following vulnerability has been resolved: netfilter: xtables: avoid NFPROTOUNSPEC where needed syzbot managed to call xtcluster match via ebtables: WARNING: CPU: 0 PID: 11 at net/netfilter/xtcluster.c:72 xtclustermt+0x196/0x780 .. ebtdotable+0x174b/0x2a40 Module register...