netfilter: nf_tables: remove nft_af_info.

The struct nft_af_info was removed.
Signed-off-by: NTaehee Yoo <ap420073@gmail.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

include/net/netns/nftables.h

@@ -4,8 +4,6 @@
 
 #include <linux/list.h>
 
-struct nft_af_info;
-
 struct netns_nftables {
 	struct list_head	tables;
 	struct list_head	commit_list;