net: Call skb_get_hash in get_xps_queue and __skb_tx_hash

Call standard function to get a packet hash instead of taking this from
skb->sk->sk_hash or only using skb->protocol.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index ec89301..b297af7 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -3005,7 +3005,7 @@
 	return skb->queue_mapping != 0;
 }
 
-u16 __skb_tx_hash(const struct net_device *dev, const struct sk_buff *skb,
+u16 __skb_tx_hash(const struct net_device *dev, struct sk_buff *skb,
 		  unsigned int num_tx_queues);
 
 static inline struct sec_path *skb_sec_path(struct sk_buff *skb)