ndisc: Add missing strategies for per-device retrans timer/reachable time settings.

Noticed from Al Viro <viro@ftp.linux.org.uk> via David Miller
<davem@davemloft.net>.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ndisc.h b/include/net/ndisc.h
index 9c451ff..a01b7c4 100644
--- a/include/net/ndisc.h
+++ b/include/net/ndisc.h
@@ -129,6 +129,10 @@
 							   void __user *buffer,
 							   size_t *lenp,
 							   loff_t *ppos);
+int ndisc_ifinfo_sysctl_strategy(ctl_table *ctl, int __user *name,
+				 int nlen, void __user *oldval,
+				 size_t __user *oldlenp,
+				 void __user *newval, size_t newlen);
 #endif
 
 extern void 			inet6_ifinfo_notify(int event,