thermal/of: Fix reference leak in thermal_of_cm_lookup()

In the Linux kernel, the following vulnerability has been resolved: thermal/of: Fix reference leak in thermal_of_cm_lookup() In thermal_of_cm_lookup(), tr_np is obtained via of_parse_phandle(), but never released. Use the __free(device_node) cleanup attribute to automatically release the node and fix the leak. [ rjw: Changelog edits ]