ACPI / hotplug / PCI: Mark stale PCI devices disconnected

Following PCIehp mark the unplugged PCI devices disconnected.  This makes
sure PCI core code leaves the now missing hardware registers alone.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>