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/udp.c b/net/ipv6/udp.c
index 69ebdbe..34efb35 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1396,7 +1396,7 @@
 	},
 };
 
-int udp6_proc_init(struct net *net)
+int __net_init udp6_proc_init(struct net *net)
 {
 	return udp_proc_register(net, &udp6_seq_afinfo);
 }