cxgb4vf: don't implement trivial (and incorrect) ndo_select_queue()

Don't implement (struct net_device_ops *)->ndo_select_queue() with simple
call to skb_tx_hash().  This leads to non-persistent TX queue selection in
the Linux dev_pick_tx() routine for TCP connections.

Signed-off-by: Casey Leedom <leedom@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>