netfilter: ipset: Validate the set family and not the set type family at swapping

This closes netfilter bugzilla #843, reported by Quentin Armitage.

Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c
index c8c303c..f2e30fb 100644
--- a/net/netfilter/ipset/ip_set_core.c
+++ b/net/netfilter/ipset/ip_set_core.c
@@ -1052,7 +1052,7 @@
 	 * Not an artificial restriction anymore, as we must prevent
 	 * possible loops created by swapping in setlist type of sets. */
 	if (!(from->type->features == to->type->features &&
-	      from->type->family == to->type->family))
+	      from->family == to->family))
 		return -IPSET_ERR_TYPE_MISMATCH;
 
 	strncpy(from_name, from->name, IPSET_MAXNAMELEN);