thermal: netlink: Pass pointers to thermal_notify_tz_trip_up/down()

Instead of requiring the callers of thermal_notify_tz_trip_up/down() to
provide specific values needed to populate struct param in them, make
them extract those values from objects passed by the callers via const
pointers.

No intentional functional impact.

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