qdev: tag isabus-bridge as no-user

isabus-bridge isn't supposed to be added via -device ...

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

hw/isa-bus.c

@@ -145,6 +145,7 @@ static SysBusDeviceInfo isabus_bridge_info = {
     .init = isabus_bridge_init,
     .qdev.name  = "isabus-bridge",
     .qdev.size  = sizeof(SysBusDevice),
+    .qdev.no_user = 1,
 };
 
 static void isabus_register_devices(void)