lol, I had the same issue with that chipset locked to GB. I had to customize a db.txt like this:
country GB:
(2402 - 2482 @ 40), (N/A, 27)
(5170 - 5250 @ 40), (N/A, 27)
(5250 - 5330 @ 40), (N/A, 27), DFS
(5490 - 5710 @ 40), (N/A, 27), DFS
But then ...
country GB:
(2402 - 2482 @ 40), (N/A, 27)
(5170 - 5250 @ 40), (N/A, 27)
(5250 - 5330 @ 40), (N/A, 27), DFS
(5490 - 5710 @ 40), (N/A, 27), DFS
But then ...