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/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index f36ce15..7631b20 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -1307,7 +1307,7 @@
 	}
 }
 
-static int ipgre_init_net(struct net *net)
+static int __net_init ipgre_init_net(struct net *net)
 {
 	struct ipgre_net *ign = net_generic(net, ipgre_net_id);
 	int err;
@@ -1334,7 +1334,7 @@
 	return err;
 }
 
-static void ipgre_exit_net(struct net *net)
+static void __net_exit ipgre_exit_net(struct net *net)
 {
 	struct ipgre_net *ign;
 	LIST_HEAD(list);