Device properties framework updates for 4.21-rc1 - Introduce "software nodes", analogous to the DT and ACPI firmware nodes except that they can be created by kernel code, in order to complement fwnodes representing real firmware nodes when they are incomplete (for example missing device properties) and to supply the primary fwnode when the firmware lacks hardware description for a device completely, and replace the "property_set" struct fwnode_handle type with software nodes (Heikki Krogerus). - Clean up the just introduced software nodes support and fix a commet in the graph-handling code (Colin Ian King, Marco Felsch).