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 --cc include/linux/netdevice.h
Simple merge

diff --cc include/linux/skbuff.h
Simple merge

diff --cc net/core/flow_dissector.c
Simple merge