wifi: iwlwifi: mvm: clarify fw_id_to_link_sta protection

This is written only with wiphy and mvm mutexes held, but in
order to actually rely on that document it and add lockdep
assertions to ensure it.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20241028135215.a6c6aa4147cf.If7f1b30a7b92ce5e9226e8972201a20aa9905108@changeid


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