xen-netfront: Call dev_kfree_skb_any instead of dev_kfree_skb.

Replace dev_kfree_skb with dev_kfree_skb_any in xennet_start_xmit
which can be called in hard irq and other contexts.  xennet_start_xmit
only fress skbs which it drops.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

drivers/net/xen-netfront.c

@@ -658,7 +658,7 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
 
  drop:
 	dev->stats.tx_dropped++;
-	dev_kfree_skb(skb);
+	dev_kfree_skb_any(skb);
 	return NETDEV_TX_OK;
 }