wifi: cfg80211: Include operating class 137 in 6GHz band

Draft P802.11be_D3.1 added operating class to describe 320 MHz
operation in the 6GHz band. Include this new operating class in
ieee80211_operating_class_to_band().

Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230928172905.bed4a007d81b.I3eb4b8fe39c0c1a988c98a103b11a9f45a92b038@changeid


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