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/addrconf.c b/net/ipv6/addrconf.c
index fa36a67..15794fd 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -544,8 +544,7 @@
 };
 
 static int inet6_netconf_get_devconf(struct sk_buff *in_skb,
-				     struct nlmsghdr *nlh,
-				     void *arg)
+				     struct nlmsghdr *nlh)
 {
 	struct net *net = sock_net(in_skb->sk);
 	struct nlattr *tb[NETCONFA_MAX+1];
@@ -3578,7 +3577,7 @@
 };
 
 static int
-inet6_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
+inet6_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh)
 {
 	struct net *net = sock_net(skb->sk);
 	struct ifaddrmsg *ifm;
@@ -3644,7 +3643,7 @@
 }
 
 static int
-inet6_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
+inet6_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh)
 {
 	struct net *net = sock_net(skb->sk);
 	struct ifaddrmsg *ifm;
@@ -3983,8 +3982,7 @@
 	return inet6_dump_addr(skb, cb, type);
 }
 
-static int inet6_rtm_getaddr(struct sk_buff *in_skb, struct nlmsghdr *nlh,
-			     void *arg)
+static int inet6_rtm_getaddr(struct sk_buff *in_skb, struct nlmsghdr *nlh)
 {
 	struct net *net = sock_net(in_skb->sk);
 	struct ifaddrmsg *ifm;