i40e: Enable Loopback for the FCOE vsi as well

For all VSIs on a VEB, Loopback mode should be either on or off.
Our configuration requires them to be ON so that VSIs can directly
talk to each other without going out on the wire.

Change-ID: I77b8310bc846329972b13b185949ab1431a46c30
Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>