igb: Add SMBI semaphore to I210/I211

It was previously thought that, since I210/I211 are single port devices,
they did not need the SMBI semaphore. This is not the case. Add support for
the SMBI semaphore.

Signed-off-by: Matthew Vick <matthew.vick@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>