ixgbe: Fix to get FDMI HBA attributes information with X550

Check whether the FCOE support is enabled for the devices to get the
 FDMI HBA attributes information instead of checking each device id.
Also, add Model string information for X550.

Signed-off-by: Usha Ketineni <usha.k.ketineni@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>