ACPI / property: Fix subnode lookup scope for data-only subnodes

The correct scope for looking up the objects to generate data packages for
data-only subnodes pointed to by another data-only subnode is the scope
of the parent of that subnode and not the scope containing the _DSD object
at the top of the hierarchy (the latter works only if all of the objects
returning data-only subnode packages in a given hierarchy are in the same
scope).

Fix the code to work as expected.

Fixes: 445b0eb0 (ACPI / property: Add support for data-only subnodes)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>