* - (-ENOTSUP) if hardware doesn't support this feature.
* - (-ENODEV) if *port* is invalid.
* - (-EIO) if device is removed.
* - (-ENOSPC) if no more MAC addresses can be added.
* - (-EINVAL) if MAC address is invalid.
*/
* - (-ENOTSUP) if hardware doesn't support this feature.
* - (-ENODEV) if *port* is invalid.
* - (-EIO) if device is removed.
* - (-ENOSPC) if no more MAC addresses can be added.
* - (-EINVAL) if MAC address is invalid.
*/