dnet: enable transmit time stamping.

This patch enables software (and phy device) transmit time stamping
in the "Dave ethernet interface." Compile tested only.

Cc: Ilya Yanok <yanok@emcraft.com>
Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
Signed-off-by: David S. Miller <davem@conan.davemloft.net>

drivers/net/dnet.c

@@ -588,6 +588,8 @@ static netdev_tx_t dnet_start_xmit(struct sk_buff *skb, struct net_device *dev)
 		dnet_writel(bp, irq_enable, INTR_ENB);
 	}
 
+	skb_tx_timestamp(skb);
+
 	/* free the buffer */
 	dev_kfree_skb(skb);