netfilter: nf_tables: allow to fetch set elements when table has an owner

NFT_MSG_GETSETELEM returns -EPERM when fetching set elements that belong
to table that has an owner. This results in empty set/map listing from
userspace.

Fixes: 6001a930 ("netfilter: nftables: introduce table ownership")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_api.c

@@ -5487,7 +5487,7 @@ static int nf_tables_getsetelem(struct sk_buff *skb,
 	int rem, err = 0;
 
 	table = nft_table_lookup(net, nla[NFTA_SET_ELEM_LIST_TABLE], family,
-				 genmask, NETLINK_CB(skb).portid);
+				 genmask, 0);
 	if (IS_ERR(table)) {
 		NL_SET_BAD_ATTR(extack, nla[NFTA_SET_ELEM_LIST_TABLE]);
 		return PTR_ERR(table);