ixgbe: Enable jumbo frame for FCoE feature in 82599

Enable jumbo frame when FCoE feature is enabled in 82599. Use 3K
as the receive queue buffer size for receive queues used by FCoE
to address for max Fiber Channel frame size as 2148 bytes (with
max 2112 bytes of payload).

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>