'-h' is a valid option, recognize it

This completes commit e562a948.

Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Handle virtio network devices.

Just like virtio scsi devices, look up their bus/device/function by the
virtio device instead of the traditional way.

Signed-off-by: Peter Jones <pjones@redhat.com>
Tested-and-reviewed-by: Laszlo Ersek <lersek@redhat.com>
Correctly fill out sa_family for MAC address device types.

Signed-off-by: Peter Jones <pjones@redhat.com>