wifi: mac80211: restrict public action ECSA frame handling

wifi: mac80211: restrict public action ECSA frame handling

Public action extended channel switch announcement (ECSA)
frames cannot be protected well, the spec is unclear about
what should happen in the presence of stations that can
receive protected dual and stations that cannot.

Mitigate these issues by not treating public action frames
as the absolute truth, only treat them as a hint to stop
transmitting (quiet mode), and do the remainder of the CSA
handling only when receiving the next beacon (or protected
action frame) that contains the CSA; or, if it doesn't,
simply stop being quiet and continue operating normally.

This limits the exposure to malicious ECSA public action
frames, since they cannot cause a disconnect now, only a
short interruption in traffic.

Reviewed-by: Miriam Rachel Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20240612143037.ec7ccc45903e.Ife17d55c7ecbf98060f9c52889f3c8ba48798970@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>