netfilter: x_tables: move hook state into xt_action_param structure

Place pointer to hook state in xt_action_param structure instead of
copying the fields that we need. After this change xt_action_param fits
into one cacheline.

This patch also adds a set of new wrapper functions to fetch relevant
hook state structure fields.

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

net/netfilter/xt_ipvs.c

diff --git a/net/netfilter/xt_ipvs.c b/net/netfilter/xt_ipvs.c
index 71a9d95..0fdc890 100644
--- a/net/netfilter/xt_ipvs.c
+++ b/net/netfilter/xt_ipvs.c
@@ -48,9 +48,9 @@ static bool
 ipvs_mt(const struct sk_buff *skb, struct xt_action_param *par)
 {
 	const struct xt_ipvs_mtinfo *data = par->matchinfo;
-	struct netns_ipvs *ipvs = net_ipvs(par->net);
+	struct netns_ipvs *ipvs = net_ipvs(xt_net(par));
 	/* ipvs_mt_check ensures that family is only NFPROTO_IPV[46]. */
-	const u_int8_t family = par->family;
+	const u_int8_t family = xt_family(par);
 	struct ip_vs_iphdr iph;
 	struct ip_vs_protocol *pp;
 	struct ip_vs_conn *cp;