thermal: core: Eliminate writable trip points masks

All of the thermal_zone_device_register_with_trips() callers pass zero
writable trip points masks to it, so drop the mask argument from that
function and update all of its callers accordingly.

This also removes the artificial trip points per zone limit of 32,
related to using writable trip points masks.

No intentional functional impact.

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