wifi: iwlwifi: add CQM event support for per-link RSSI changes

wifi: iwlwifi: add CQM event support for per-link RSSI changes

Implement CQM RSSI threshold handling by tracking the last reported RSSI
and issuing CQM low/high events when the RSSI crosses the configured
threshold with the required hysteresis. This provides proper CQM support
and enables userspace to receive per-link RSSI notifications.

Signed-off-by: Avinash Bhatt <avinash.bhatt@intel.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: Pagadala Yesu Anjaneyulu <pagadala.yesu.anjaneyulu@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20260320100746.08697e34bf66.Ic1a68537ef0d37be62c73c138efe9c5cf09bd24c@changeid