net: bcmgenet: add skb_tx_timestamp call

The BCMGENET driver was not TX timestamping the SKBs it queued for
transmission, do this in bcmgenet_xmit() right before kicking the
Transmit DMA engine.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/genet/bcmgenet.c

@@ -1176,6 +1176,8 @@ static netdev_tx_t bcmgenet_xmit(struct sk_buff *skb, struct net_device *dev)
 		}
 	}
 
+	skb_tx_timestamp(skb);
+
 	/* we kept a software copy of how much we should advance the TDMA
 	 * producer index, now write it down to the hardware
 	 */