igb: Add workaround for byte swapped VLAN on i350 local traffic

On i350 when traffic is looped back from a VF to the PF the value is byte
swapped from the normal format.  In order to address this we need to add a
flag indicating that the ring will need to byte swap the loopback packets
prior to processing them.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>