nft: fix match revision lookup for IPv6

IPT_SO_GET_REVISION_MATCH != IP6T_SO_GET_REVISION_MATCH, thus,
the revision infrastructure was looking for targets instead
matches.
diff --git a/iptables/nft.c b/iptables/nft.c
index 68fc153..bbe5e39 100644
--- a/iptables/nft.c
+++ b/iptables/nft.c
@@ -2730,7 +2730,8 @@
 	uint32_t portid, seq, type;
 	int ret = 0;
 
-	if (opt == IPT_SO_GET_REVISION_MATCH)
+	if (opt == IPT_SO_GET_REVISION_MATCH ||
+	    opt == IP6T_SO_GET_REVISION_MATCH)
 		type = 0;
 	else
 		type = 1;