netfilter: nf_tables: add single table list for all families

Place all existing user defined tables in struct net *, instead of
having one list per family. This saves us from one level of indentation
in netlink dump functions.

Place pointer to struct nft_af_info in struct nft_table temporarily, as
we still need this to put back reference module reference counter on
table removal.

This patch comes in preparation for the removal of struct nft_af_info.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netns/nftables.h

@@ -8,6 +8,7 @@ struct nft_af_info;
 
 struct netns_nftables {
 	struct list_head	af_info;
+	struct list_head	tables;
 	struct list_head	commit_list;
 	struct nft_af_info	*ipv4;
 	struct nft_af_info	*ipv6;