ixgbe: Add support for multiple Tx queues for FCoE in 82599

This patch adds support for multiple transmit queues to the Fiber Channel
over Ethernet (FCoE) feature found in 82599. Currently, FCoE has multiple
Rx queues available, along with a redirection table, that helps distribute
the I/O load across multiple CPUs based on the FC exchange ID. To make
this the most effective, we need to provide the same layout of transmit
queues to match receive.

Particularly, when Data Center Bridging (DCB) is enabled, the designated
traffic class for FCoE can have dedicated queues for just FCoE traffic,
while not affecting any other type of traffic flow.

Signed-off-by: Yi Zou <yi.zou@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>