igb: Enable nfc filters to specify MAC addresses

This allows igb_add_filter()/igb_erase_filter() to work on filters
that include MAC addresses (both source and destination).

For now, this only exposes the functionality, the next commit glues
ethtool into this. Later in this series, these APIs are used to allow
offloading of cls_flower filters.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>