IPoIB: Free child interfaces properly

When deleting a child interface with a non-default P_Key via
/sys/class/net/ibX/delete_child, the interface must be freed with
free_netdev() (rather than kfree() on the private data).
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/ulp/ipoib/ipoib_vlan.c

@@ -158,10 +158,8 @@ int ipoib_vlan_delete(struct net_device *pdev, unsigned short pkey)
 		if (priv->pkey == pkey) {
 			unregister_netdev(priv->dev);
 			ipoib_dev_cleanup(priv->dev);
-
 			list_del(&priv->list);
-
-			kfree(priv);
+			free_netdev(priv->dev);
 
 			ret = 0;
 			break;