ixgbe: select FCoE Tx queue in ndo_select_queue

This removes the Tx queue selection for FCoE traffic from ixgbe_xmit_frame()
and does it in the ndo_select_queue() call, moving all Tx queue selection
into a single routine.

Signed-off-by: Yi Zou <yi.zou@intel.com>
Acked-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>