mac80211_hwsim: indicate support for S1G

Advertise S1G Capabilities and channels to mac80211.

Requires a few fixups to account for missing
sband->bitrates, and a custom regulatory db to actually
enable the S1G channels.

Signed-off-by: Thomas Pedersen <thomas@adapt-ip.com>
Link: https://lore.kernel.org/r/20200922022818.15855-18-thomas@adapt-ip.com


[small code cleanup]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>