wifi: iwlwifi: mvm: support 320 MHz PHY configuration

Support 320 MHz PHY configuration and while doing so rewrite
the code since we'd otherwise double the number of cases in
the switch statement.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Link: https://lore.kernel.org/r/20221122220713.964db911b733.If56c94a9bf20c050f35d2421b680e400a9f4aeb8@changeid


Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>