[NETFILTER] nat: remove bogus structure member

When 'rustynat' was merged in 2.6.12, the use of the "helper" pointer of
struct ipt_nat_info was obsoleted, but the pointer not removed from the
struct.

This patch removes the pointer, thereby yet again shrinking struct
ip_conntrack.

Discovered-by: Rusty Russell <rusty@netfilter.org>
Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netfilter_ipv4/ip_nat.h

@@ -58,10 +58,6 @@ extern rwlock_t ip_nat_lock;
 struct ip_nat_info
 {
 	struct list_head bysource;
-
-	/* Helper (NULL if none). */
-	struct ip_nat_helper *helper;
-
 	struct ip_nat_seq seq[IP_CT_DIR_MAX];
 };