pxa168_eth: enable transmit time stamping.

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

Cc: Sachin Sanap <ssanap@marvell.com>
Cc: Zhangfei Gao <zgao6@marvell.com>
Cc: Philip Rakity <prakity@marvell.com>
Cc: Mark Brown <markb@marvell.com>
Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/pxa168_eth.c

@@ -1267,6 +1267,9 @@ static int pxa168_eth_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	pep->tx_skb[tx_index] = skb;
 	desc->byte_cnt = length;
 	desc->buf_ptr = dma_map_single(NULL, skb->data, length, DMA_TO_DEVICE);
+
+	skb_tx_timestamp(skb);
+
 	wmb();
 	desc->cmd_sts = BUF_OWNED_BY_DMA | TX_GEN_CRC | TX_FIRST_DESC |
 			TX_ZERO_PADDING | TX_LAST_DESC | TX_EN_INT;