hwmon: (tmp421) Add of_node_put() before return

Fix following coccicheck warning:
./drivers/hwmon/tmp421.c:416:1-23: WARNING: Function
for_each_child_of_node should have of_node_put() before return.

Early exits from for_each_child_of_node should decrement the
node reference counter.

Signed-off-by: Wan Jiabing <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Guenter Roeck <[e-mail]>

drivers/hwmon/tmp421.c

···
 			continue;
 
 		err = tmp421_probe_child_from_dt(client, child, data);
-		if (err)
+		if (err) {
+			of_node_put(child);
 			return err;
+		}
 	}
 
 	return 0;