e1000: 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/e1000/e1000_main.c

@@ -3261,6 +3261,8 @@ static netdev_tx_t e1000_xmit_frame(struct sk_buff *skb,
 	                     nr_frags, mss);
 
 	if (count) {
+		skb_tx_timestamp(skb);
+
 		e1000_tx_queue(adapter, tx_ring, tx_flags, count);
 		/* Make sure there is space in the ring for the next send. */
 		e1000_maybe_stop_tx(netdev, tx_ring, MAX_SKB_FRAGS + 2);