device property: Add support for remote endpoints

This follows DT implementation of of_graph_* APIs but we call them
fwnode_graph_* instead. For DT nodes the existing of_graph_* implementation
will be used. For ACPI we use the new ACPI graph implementation instead.

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