rtnetlink: ignore NETDEV_RELEASE and NETDEV_JOIN event

These two events are not expected to be caught by userspace.
Signed-off-by: NWANG Cong <amwang@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/rtnetlink.c

@@ -1956,6 +1956,8 @@ static int rtnetlink_event(struct notifier_block *this, unsigned long event, voi
 	case NETDEV_GOING_DOWN:
 	case NETDEV_UNREGISTER:
 	case NETDEV_UNREGISTER_BATCH:
+	case NETDEV_RELEASE:
+	case NETDEV_JOIN:
 		break;
 	default:
 		rtmsg_ifinfo(RTM_NEWLINK, dev, 0);