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

Noticed from Al Viro <[e-mail]> via David Miller
<[e-mail]>.

Signed-off-by: YOSHIFUJI Hideaki <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/ndisc.h

···
 							   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,

net/ipv6/addrconf.c

···
 	neigh_sysctl_register(idev->dev, idev->nd_parms, NET_IPV6,
 			      NET_IPV6_NEIGH, "ipv6",
 			      &ndisc_ifinfo_sysctl_change,
-			      NULL);
+			      ndisc_ifinfo_sysctl_strategy);
 	__addrconf_sysctl_register(dev_net(idev->dev), idev->dev->name,
 			idev->dev->ifindex, idev, &idev->cnf);
 }

net/ipv6/ndisc.c

···
 	return ret;
 }
 
-static 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)
+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)
 {
 	struct net_device *dev = ctl->extra1;
 	struct inet6_dev *idev;