iwlwifi: mvm: Use for_each_thermal_trip() for walking trip points

The code walking trip points in iwl_mvm_send_temp_report_ths_cmd()
reads the trip table passed to thermal_zone_device_register_with_trips()
in order to get the current trip temperatures, but this is not
guaranteed to work in the future, because the thermal zone will store
trip points information internally.

For this reason, make iwl_mvm_send_temp_report_ths_cmd() use
for_each_thermal_trip() as appropriate for walking trip points in a
given thermal zone.

No intentional functional impact, but it is requisite for future thermal
core improvements.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Miri Korenblit <Miriam.rachel.korenblit@intel.com>