thermal: of-thermal: disable passive polling when thermal zone is disabled

When thermal zone is in passive mode, disabling its mode from
sysfs is NOT taking effect at all, it is still polling the
temperature of the disabled thermal zone and handling all thermal
trips, it makes user confused. The disabling operation should
disable the thermal zone behavior completely, for both active and
passive mode, this patch clears the passive_delay when thermal
zone is disabled and restores it when it is enabled.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>