ipv6: Do cleanup for ip6_mr_init.

If do not do it, we will get following issues:
1. Leaving junks after inet6_init failing halfway.
2. Leaving proc and notifier junks after ipv6 modules unloading.

Signed-off-by: Wang Chen <wangchen@cn.fujitsu.com>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
diff --git a/include/linux/mroute6.h b/include/linux/mroute6.h
index e798959..4c4d6f5 100644
--- a/include/linux/mroute6.h
+++ b/include/linux/mroute6.h
@@ -135,7 +135,8 @@
 extern int ip6_mroute_getsockopt(struct sock *, int, char __user *, int __user *);
 extern int ip6_mr_input(struct sk_buff *skb);
 extern int ip6mr_ioctl(struct sock *sk, int cmd, void __user *arg);
-extern void ip6_mr_init(void);
+extern int ip6_mr_init(void);
+extern void ip6_mr_cleanup(void);
 
 struct mif_device
 {