e1000e: add transmit timestamping support

Signed-off-by: NWillem de Bruijn <willemb@google.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/e1000e/netdev.c

@@ -5131,6 +5131,8 @@ static netdev_tx_t e1000_xmit_frame(struct sk_buff *skb,
 	/* if count is 0 then mapping error has occurred */
 	count = e1000_tx_map(tx_ring, skb, first, max_per_txd, nr_frags, mss);
 	if (count) {
+		skb_tx_timestamp(skb);
+
 		netdev_sent_queue(netdev, skb->len);
 		e1000_tx_queue(tx_ring, tx_flags, count);
 		/* Make sure there is space in the ring for the next send. */