netfilter: nft_meta: permit pkttype mangling in ip/ip6 prerouting

After supporting this, we can combine it with hash expression to emulate
the 'cluster match'.
Suggested-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Liping Zhang <liping.zhang@spreadtrum.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_meta.c

@@ -310,6 +310,11 @@ int nft_meta_set_validate(const struct nft_ctx *ctx,
 	case NFPROTO_NETDEV:
 		hooks = 1 << NF_NETDEV_INGRESS;
 		break;
+	case NFPROTO_IPV4:
+	case NFPROTO_IPV6:
+	case NFPROTO_INET:
+		hooks = 1 << NF_INET_PRE_ROUTING;
+		break;
 	default:
 		return -EOPNOTSUPP;
 	}