forcedeth: add transmit timestamping support

Insert an skb_tx_timestamp call in both ndo_start_xmit routines
Tested to work for the nv_start_xmit_optimized case

Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/nvidia/forcedeth.c

@@ -2279,6 +2279,8 @@ static netdev_tx_t nv_start_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	netdev_sent_queue(np->dev, skb->len);
 
+	skb_tx_timestamp(skb);
+
 	np->put_tx.orig = put_tx;
 
 	spin_unlock_irqrestore(&np->lock, flags);
@@ -2426,6 +2428,8 @@ static netdev_tx_t nv_start_xmit_optimized(struct sk_buff *skb,
 
 	netdev_sent_queue(np->dev, skb->len);
 
+	skb_tx_timestamp(skb);
+
 	np->put_tx.ex = put_tx;
 
 	spin_unlock_irqrestore(&np->lock, flags);