netfilter: pass 'nf_hook_ops' instead of 'list_head' to nf_iterate()

Since 'list_for_each_continue_rcu' has already been replaced by
'list_for_each_entry_continue_rcu', pass 'list_head' to nf_iterate() as a
parameter can not benefit us any more.

This patch will replace 'list_head' with 'nf_hook_ops' as the parameter of
nf_iterate() to save code.

Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/netfilter/nf_internals.h b/net/netfilter/nf_internals.h
index 770f764..2886231 100644
--- a/net/netfilter/nf_internals.h
+++ b/net/netfilter/nf_internals.h
@@ -18,7 +18,7 @@
 				unsigned int hook,
 				const struct net_device *indev,
 				const struct net_device *outdev,
-				struct list_head **i,
+				struct nf_hook_ops **elemp,
 				int (*okfn)(struct sk_buff *),
 				int hook_thresh);