[IPV6]: Add ndisc_netdev_notifier unregister.

If inet6_init() fails later than ndisc_init() call, or IPv6 module is
unloaded, ndisc_netdev_notifier call remains in the list and will follows in
oops later.

Signed-off-by: Dmitry Mishin <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/ipv6/ndisc.c

···
 
 void ndisc_cleanup(void)
 {
+	unregister_netdevice_notifier(&ndisc_netdev_notifier);
 #ifdef CONFIG_SYSCTL
 	neigh_sysctl_unregister(&nd_tbl.parms);
 #endif