RTL8812AU / RTL8821AU driver - call for testing

[Andriy Voskoboinyk]

Hi all!

The driver is in https://github.com/s3erios/urtwm ; currently it includes  
most
features from urtwn(4) + TCP/UDP/IP checksum validation. 11a is supported  
too
(but without DFS at this moment).

Seems to be stable enough with DLINK DWA-171 (RTL8821AU)
(11a/b/g support was tested only; you can try to enable 11n Rx support by  
adding
"hw.usb.urtwm.enable_11n=1" into /boot/loader.conf).