ACPI: thermal: Use thermal_zone_for_each_trip() for updating trips

Rearrange the code handling notifications from the platform firmware
regarding trip point updates to carry out one loop over trip points
instead of two of them by using thermal_zone_for_each_trip() for that,
which is more straightforward than using a combination of
thermal_zone_device_exec() and for_each_thermal_trip(), each with its
own callback function.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>