ixgbe: Add RING_F_FCOE for FCoE feature in 82599

Add ring feature for FCoE to make use of the FCoE redirection
table in 82599. The FCoE redirection table is a receive side
scaling feature for Fiber Channel over Ethernet feature in 82599,
enabling distributing FCoE packets to different receive queues
based on the exchange id.

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>