hw/ppc: realize the PCI root bus as part of mac99 init

Mac99's PCI root bus is not part of a host bridge,
realize it manually.
Signed-off-by: NMarcel Apfelbaum <marcel@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

hw/ppc/mac_newworld.c

@@ -380,6 +380,7 @@ static void ppc_core99_init(MachineState *machine)
         pci_bus = pci_pmac_init(pic, get_system_memory(), get_system_io());
         machine_arch = ARCH_MAC99;
     }
+    object_property_set_bool(OBJECT(pci_bus), true, "realized", &error_abort);
 
     machine->usb |= defaults_enabled() && !machine->usb_disabled;