cfg80211: regulatory: handle S1G channels

S1G channels have a minimum bandwidth of 1Mhz, and there
is a 1:1 mapping of allowed bandwidth to channel number.

Signed-off-by: Thomas Pedersen <thomas@adapt-ip.com>
Link: https://lore.kernel.org/r/20200908190323.15814-4-thomas@adapt-ip.com


Signed-off-by: Johannes Berg <johannes.berg@intel.com>