thermal: core: Drop tz field from struct thermal_instance

After recent changes, it is only used for printing a debug message
in __thermal_cdev_update() which arguably is not worth preserving.

Drop it along with the dev_dbg() statement using it.

Link: https://lore.kernel.org/linux-pm/4a8d8f5a-122d-4c26-b8d6-76a65e42216b@linaro.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://patch.msgid.link/4934182.GXAFRqVoOG@rjwysocki.net

drivers/thermal/thermal_core.c

@@ -804,7 +804,7 @@ static int thermal_bind_cdev_to_trip(struct thermal_zone_device *tz,
 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 	if (!dev)
 		return -ENOMEM;
-	dev->tz = tz;
+
 	dev->cdev = cdev;
 	dev->trip = trip;
 	dev->upper = cool_spec->upper;

drivers/thermal/thermal_core.h

@@ -213,7 +213,6 @@ int get_tz_trend(struct thermal_zone_device *tz, const struct thermal_trip *trip
 struct thermal_instance {
 	int id;
 	char name[THERMAL_NAME_LENGTH];
-	struct thermal_zone_device *tz;
 	struct thermal_cooling_device *cdev;
 	const struct thermal_trip *trip;
 	bool initialized;

drivers/thermal/thermal_helpers.c

@@ -181,8 +181,6 @@ void __thermal_cdev_update(struct thermal_cooling_device *cdev)
 
 	/* Make sure cdev enters the deepest cooling state */
 	list_for_each_entry(instance, &cdev->thermal_instances, cdev_node) {
-		dev_dbg(&cdev->device, "zone%d->target=%lu\n",
-			instance->tz->id, instance->target);
 		if (instance->target == THERMAL_NO_TARGET)
 			continue;
 		if (instance->target > target)