hw/qdev: Constify DeviceState* argument of qdev_get_parent_bus()

The structure is accessed read-only by qdev_get_parent_bus().

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230212224730.51438-2-philmd@linaro.org>

hw/core/qdev.c

@@ -330,7 +330,7 @@ bool qdev_machine_modified(void)
     return qdev_hot_added || qdev_hot_removed;
 }
 
-BusState *qdev_get_parent_bus(DeviceState *dev)
+BusState *qdev_get_parent_bus(const DeviceState *dev)
 {
     return dev->parent_bus;
 }

include/hw/qdev-core.h

@@ -715,7 +715,7 @@ static inline void qdev_init_gpio_in_named(DeviceState *dev,
 void qdev_pass_gpios(DeviceState *dev, DeviceState *container,
                      const char *name);
 
-BusState *qdev_get_parent_bus(DeviceState *dev);
+BusState *qdev_get_parent_bus(const DeviceState *dev);
 
 /*** BUS API. ***/