Phonet: device notifier only runs on initial namespace

[bwh: This is only applicable to 2.6.32. Phonet was fixed upstream to
work with multiple net namespaces.]

This should really fix the OOPS when doing:

  unshare(CLONE_NEWNET);
  exit(0);

while the phonet module is loaded.
Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

net/phonet/pn_dev.c

@@ -225,6 +225,9 @@ static int phonet_device_notify(struct notifier_block *me, unsigned long what,
 {
 	struct net_device *dev = arg;
 
+	if (!net_eq(dev_net(dev), &init_net))
+		return 0;
+
 	switch (what) {
 	case NETDEV_REGISTER:
 		if (dev->type == ARPHRD_PHONET)