DFS: Mark channels required DFS based on reg-domain info from the driver

DFS: Mark channels required DFS based on reg-domain info from the driver

Mark a channel as required DFS based on regulatory information received
from the driver/kernel rather than deciding based on hardcoded
boundaries on the frequency. Previously few channels were being marked
as requiring DFS even though they were non-DFS in a particular country.

If the driver does not provide channel list information, fall back to
the previously used frequency-based determination.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>