thermal: core: Introduce .manage() callback for thermal governors

Introduce a new thermal governor callback called .manage() that will be
invoked once per thermal zone update after processing all of the trip
points in the core.

This will allow governors that look at multiple trip points together
to check all of them in a consistent configuration, so they don't need
to play tricks with skipping .throttle() invocations that they are not
interested in and they can avoid carrying out the same computations for
multiple times in one cycle.

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