qom: Constify TypeInfo::class_data

All callers now correctly expect a const class data.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20250424194905.82506-5-philmd@linaro.org>

hw/sensor/tmp421.c

@@ -382,7 +382,7 @@ static void tmp421_register_types(void)
             .name       = devices[i].name,
             .parent     = TYPE_TMP421,
             .class_init = tmp421_class_init,
-            .class_data = (void *) &devices[i],
+            .class_data = &devices[i],
         };
         type_register_static(&ti);
     }