mv643xx_eth: enable transmit time stamping.

This patch enables software (and phy device) transmit time stamping.
Compile tested only.

Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/mv643xx_eth.c b/drivers/net/mv643xx_eth.c
index 1b7d2c1..77dc6ab 100644
--- a/drivers/net/mv643xx_eth.c
+++ b/drivers/net/mv643xx_eth.c
@@ -840,6 +840,8 @@
 
 	__skb_queue_tail(&txq->tx_skb, skb);
 
+	skb_tx_timestamp(skb);
+
 	/* ensure all other descriptors are written before first cmd_sts */
 	wmb();
 	desc->cmd_sts = cmd_sts;