net: fix a build failure when !CONFIG_PROC_FS

When !CONFIG_PROC_FS dev_mcast_init() is not defined,
actually we can just merge dev_mcast_init() into
dev_proc_init().

Reported-by: Gao feng <gaofeng@cn.fujitsu.com>
Cc: Gao feng <gaofeng@cn.fujitsu.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/net-procfs.c b/net/core/net-procfs.c
index ac87066..0f6bb6f 100644
--- a/net/core/net-procfs.c
+++ b/net/core/net-procfs.c
@@ -341,11 +341,6 @@
 	.exit = dev_proc_net_exit,
 };
 
-int __init dev_proc_init(void)
-{
-	return register_pernet_subsys(&dev_proc_ops);
-}
-
 static int dev_mc_seq_show(struct seq_file *seq, void *v)
 {
 	struct netdev_hw_addr *ha;
@@ -408,7 +403,10 @@
 	.exit = dev_mc_net_exit,
 };
 
-void __init dev_mcast_init(void)
+int __init dev_proc_init(void)
 {
-	register_pernet_subsys(&dev_mc_net_ops);
+	int ret = register_pernet_subsys(&dev_proc_ops);
+	if (!ret)
+		return register_pernet_subsys(&dev_mc_net_ops);
+	return ret;
 }