drm/logicvc: Fix device node reference leak in logicvc_drm_config_parse()

In the Linux kernel, the following vulnerability has been resolved: drm/logicvc: Fix device node reference leak in logicvc_drm_config_parse() The logicvc_drm_config_parse() function calls of_get_child_by_name() to find the "layers" node but fails to release the reference, leading to a device node reference leak. Fix this by using the __free(device_node) cleanup attribute to automatic release the reference when the variable goes out of scope.