When parsing resources for PCI host bridge, we should ignore resources
consumed by host bridge itself and only report window resources available
to child PCI busses.

Fixes: 593669c2 (x86/PCI/ACPI: Use common ACPI resource interfaces ...)
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>