igc: Remove 'queue' check in igc_del_mac_filter()

igc_add_mac_filter() doesn't allow us to have more than one entry with
the same address and address type in adapter->mac_table so checking if
'queue' matches in igc_del_mac_filter() isn't necessary. This patch
removes that check.

This patch also takes the opportunity to improve the igc_del_mac_filter
documentation and remove comment which is not applicable to this I225
controller.

Signed-off-by: Andre Guedes <andre.guedes@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>