thermal: disable polling if passive_delay and polling_delay are both unset

Otherwise polling will continue for the thermal zone even when
it is no longer needed, for example because forced passive cooling
was disabled.

Signed-off-by: Frans Pop <elendil@planet.nl>
Acked-by: Matthew Garrett <mjg@redhat.com>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/thermal/thermal_sys.c

@@ -1019,6 +1019,8 @@ void thermal_zone_device_update(struct thermal_zone_device *tz)
 		thermal_zone_device_set_polling(tz, tz->passive_delay);
 	else if (tz->polling_delay)
 		thermal_zone_device_set_polling(tz, tz->polling_delay);
+	else
+		thermal_zone_device_set_polling(tz, 0);
 	mutex_unlock(&tz->lock);
 }
 EXPORT_SYMBOL(thermal_zone_device_update);