Convert a Wi-Fi driver to the new Wi-Fi stack

The Wi-Fi drivers has been changed to support newer protocols. So all existing wifi drivers needs to be changed and reworked to the new code base. Some of them are already converted and tested but some of them are not yet converted and tested on the real hardware. I am going to convert and test (otus -- Atheros USB IEEE 802.11a/g/n wireless network device (https://man.netbsd.org/otus.4) on TP-Link TL-WN821N which is a compatible device for this driver.