usbnet: add timestamping support

In order to make USB-to-Ethernet-adapters (depending on usbnet) support
timestamping, the "skb_defer_rx_timestamp" and "skb_tx_timestamp" function
calls are added.
Signed-off-by: Michael Riesch <michael@riesch.at>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/usb/usbnet.c

@@ -238,6 +238,10 @@ void usbnet_skb_return (struct usbnet *dev, struct sk_buff *skb)
 	netif_dbg(dev, rx_status, dev->net, "< rx, len %zu, type 0x%x\n",
 		  skb->len + sizeof (struct ethhdr), skb->protocol);
 	memset (skb->cb, 0, sizeof (struct skb_data));
+
+	if (skb_defer_rx_timestamp(skb))
+		return;
+
 	status = netif_rx (skb);
 	if (status != NET_RX_SUCCESS)
 		netif_dbg(dev, rx_err, dev->net,
@@ -1053,6 +1057,8 @@ netdev_tx_t usbnet_start_xmit (struct sk_buff *skb,
 	unsigned long		flags;
 	int retval;
 
+	skb_tx_timestamp(skb);
+
 	// some devices want funky USB-level framing, for
 	// win32 driver (usually) and/or hardware quirks
 	if (info->tx_fixup) {