rtnetlink: Remove passing of attributes into rtnl_doit functions

With decnet converted, we can finally get rid of rta_buf and its
computations around it. It also gets rid of the minimal header
length verification since all message handlers do that explicitly
anyway.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index e5fe004..ad0aa6b 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2355,7 +2355,7 @@
 	return last_err;
 }
 
-static int inet6_rtm_delroute(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
+static int inet6_rtm_delroute(struct sk_buff *skb, struct nlmsghdr* nlh)
 {
 	struct fib6_config cfg;
 	int err;
@@ -2370,7 +2370,7 @@
 		return ip6_route_del(&cfg);
 }
 
-static int inet6_rtm_newroute(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
+static int inet6_rtm_newroute(struct sk_buff *skb, struct nlmsghdr* nlh)
 {
 	struct fib6_config cfg;
 	int err;
@@ -2562,7 +2562,7 @@
 		     prefix, 0, NLM_F_MULTI);
 }
 
-static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr* nlh, void *arg)
+static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr* nlh)
 {
 	struct net *net = sock_net(in_skb->sk);
 	struct nlattr *tb[RTA_MAX+1];