Add Support for the ALFA Hornet UB and similar devices

The Hornet UB is sold at least in the varieties. Without case it is a Hornet UB, with case and without connected USB port it is called AP121. If the USB port is present this device is called AP121U.
We have a AP121U in our mesh http://meshviewer.chemnitz.freifunk.net/#!v:m;n:00c0ca6efffa