If pcie_ports_disabled is set, pcie_port_service_register() returns
error code and select_detection_mode() should not attempt to
unregister dummy_driver and use dummy_slots.  It should return
PCIEHP_DETECT_ACPI immediately instead.
Reviewed-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Acked-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
 static int __init select_detection_mode(void)
 {
        struct dummy_slot *slot, *tmp;
-       pcie_port_service_register(&dummy_driver);
+       if (pcie_port_service_register(&dummy_driver))
+               return PCIEHP_DETECT_ACPI;
        pcie_port_service_unregister(&dummy_driver);
        list_for_each_entry_safe(slot, tmp, &dummy_slots, list) {
                list_del(&slot->list);