device property: Add support for fwnode endpoints

Similar to OF endpoints, endpoint type nodes can be also supported on
ACPI. In order to make it possible for drivers to ignore the matter,
add a type for fwnode_endpoint and a function to parse them.

On ACPI, find the child node index instead of relying on the "endpoint"
property.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

include/linux/fwnode.h

@@ -27,4 +27,16 @@ struct fwnode_handle {
 	struct fwnode_handle *secondary;
 };
 
+/**
+ * struct fwnode_endpoint - Fwnode graph endpoint
+ * @port: Port number
+ * @id: Endpoint id
+ * @local_fwnode: reference to the related fwnode
+ */
+struct fwnode_endpoint {
+	unsigned int port;
+	unsigned int id;
+	const struct fwnode_handle *local_fwnode;
+};
+
 #endif