ACPI: Set flag IORESOURCE_UNSET for unassigned resources

Also set flag IORESOURCE_UNSET for unassigned resource in addition to
IORESOURCE_DISABLED to mark resource as unassigned.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>