qeth: layer 3 Oops in ip event handler

The ip event handler may present us non qeth network interfaces.
Add qeth card pointer check.

Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
index 94a8ead..b041ea8 100644
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -2070,7 +2070,7 @@
 		card = netdev_priv(dev);
 	else if (rc == QETH_VLAN_CARD)
 		card = netdev_priv(vlan_dev_info(dev)->real_dev);
-	if (card->options.layer2)
+	if (card && card->options.layer2)
 		card = NULL;
 	QETH_DBF_TEXT_(TRACE, 4, "%d", rc);
 	return card ;