igb: enable l4 timestamping for v2 event packets

When enabling hardware timestamping for ptp v2 event packets, the
software does not setup the queue for l4 packets, although layer 4
packets are valid for v2. This patch adds the flag which enables
setting up a queue and enabling udp packet timestamping.
Signed-off-by: NJacob E Keller <jacob.e.keller@intel.com>
Tested-by: NAaron Brown <aaron.f.brown@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/igb/igb_main.c

@@ -6268,6 +6268,7 @@ static int igb_hwtstamp_ioctl(struct net_device *netdev,
 		tsync_rx_ctl |= E1000_TSYNCRXCTL_TYPE_EVENT_V2;
 		config.rx_filter = HWTSTAMP_FILTER_PTP_V2_EVENT;
 		is_l2 = true;
+		is_l4 = true;
 		break;
 	default:
 		return -ERANGE;