ACPI: property: Allow direct graph endpoint references

By using device and further data node references, allow direct references
to endpoints. These are of form

	Package() { \DEV, "portX", "endpointY" }

where X is the number of the port and Y is the number of the endpoint.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/property.c

@@ -1122,9 +1122,9 @@ acpi_graph_get_remote_endpoint(const struct fwnode_handle *__fwnode)
 	if (ret)
 		return NULL;
 
-	/* Ensure this is a device node. */
+	/* Direct endpoint reference? */
 	if (!is_acpi_device_node(args.fwnode))
-		return NULL;
+		return args.nargs ? NULL : args.fwnode;
 
 	/*
 	 * Always require two arguments with the reference: port and