net: spread __net_init, __net_exit

__net_init/__net_exit are apparently not going away, so use them
to full extent.

In some cases __net_init was removed, because it was called from
__net_exit code.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index c4585279..2dfec6b 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1772,7 +1772,7 @@
 
 #endif
 
-static int ndisc_net_init(struct net *net)
+static int __net_init ndisc_net_init(struct net *net)
 {
 	struct ipv6_pinfo *np;
 	struct sock *sk;
@@ -1797,7 +1797,7 @@
 	return 0;
 }
 
-static void ndisc_net_exit(struct net *net)
+static void __net_exit ndisc_net_exit(struct net *net)
 {
 	inet_ctl_sock_destroy(net->ipv6.ndisc_sk);
 }