nft: fix family operation lookup

xtables-restore -6 was using the IPv4 family, instead of IPv6
as it should be.

Signed-off-by: Giuseppe Longo <giuseppelng@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/iptables/xtables.c b/iptables/xtables.c
index 3035546..946f04d 100644
--- a/iptables/xtables.c
+++ b/iptables/xtables.c
@@ -1110,7 +1110,7 @@
 	if (h->family == AF_UNSPEC)
 		h->family = args.family;
 
-	h->ops = nft_family_ops_lookup(args.family);
+	h->ops = nft_family_ops_lookup(h->family);
 	if (h->ops == NULL)
 		xtables_error(PARAMETER_PROBLEM, "Unknown family");