net: Kill hold_net release_net

hold_net and release_net were an idea that turned out to be useless.
The code has been disabled since 2008.  Kill the code it is long past due.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/ip6_flowlabel.c

@@ -100,7 +100,6 @@ static void fl_free(struct ip6_flowlabel *fl)
 	if (fl) {
 		if (fl->share == IPV6_FL_S_PROCESS)
 			put_pid(fl->owner.pid);
-		release_net(fl->fl_net);
 		kfree(fl->opt);
 		kfree_rcu(fl, rcu);
 	}
@@ -403,7 +402,7 @@ fl_create(struct net *net, struct sock *sk, struct in6_flowlabel_req *freq,
 		}
 	}
 
-	fl->fl_net = hold_net(net);
+	fl->fl_net = net;
 	fl->expires = jiffies;
 	err = fl6_renew(fl, freq->flr_linger, freq->flr_expires);
 	if (err)