thermal: of: Use scoped memory and OF handling to simplify thermal_of_trips_init()

Obtain the device node reference and allocate memory with
scoped/cleanup.h to reduce error handling and make the code a bit
simpler.

The code is not equivalent in one minor aspect: outgoing parameter
"*ntrips" will not be zeroed on errors of memory allocation.  This
difference is not important, because code was already not zeroing it in
case of earlier errors and the only caller does not rely on ntrips being
0 in case of errors.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://patch.msgid.link/20241010-b4-cleanup-h-of-node-put-thermal-v4-2-bfbe29ad81f4@linaro.org
[ rjw: Rebase ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: krzk

drivers/thermal/thermal_of.c

@@ -95,45 +95,32 @@ static int thermal_of_populate_trip(struct device_node *np,
 
 static struct thermal_trip *thermal_of_trips_init(struct device_node *np, int *ntrips)
 {
-	struct thermal_trip *tt;
-	struct device_node *trips;
 	int ret, count;
 
 	*ntrips = 0;
 
-	trips = of_get_child_by_name(np, "trips");
+	struct device_node *trips __free(device_node) = of_get_child_by_name(np, "trips");
 	if (!trips)
 		return NULL;
 
 	count = of_get_child_count(trips);
 	if (!count)
 		return NULL;
 
-	tt = kzalloc(sizeof(*tt) * count, GFP_KERNEL);
-	if (!tt) {
-		ret = -ENOMEM;
-		goto out_of_node_put;
-	}
-
-	*ntrips = count;
+	struct thermal_trip *tt __free(kfree) = kzalloc(sizeof(*tt) * count, GFP_KERNEL);
+	if (!tt)
+		return ERR_PTR(-ENOMEM);
 
 	count = 0;
 	for_each_child_of_node_scoped(trips, trip) {
 		ret = thermal_of_populate_trip(trip, &tt[count++]);
 		if (ret)
-			goto out_kfree;
+			return ERR_PTR(ret);
 	}
 
-	of_node_put(trips);
-
-	return tt;
-
-out_kfree:
-	kfree(tt);
-out_of_node_put:
-	of_node_put(trips);
+	*ntrips = count;
 
-	return ERR_PTR(ret);
+	return no_free_ptr(tt);
 }
 
 static struct device_node *of_thermal_zone_find(struct device_node *sensor, int id)