platform/x86: intel_cht_int33fe: Provide software nodes for the devices

Software nodes provide two features that we will need later.
1) Software nodes can have references to other software nodes.
2) Software nodes can exist before a device entry is created.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>