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>

scripts/codeconverter/codeconverter/test_regexps.py

@@ -70,7 +70,7 @@ static const TypeInfo char_file_type_info = {
             .name = armsse_variants[i].name,
             .parent = TYPE_ARMSSE,
             .class_init = armsse_class_init,
-            .class_data = (void *)&armsse_variants[i],
+            .class_data = &armsse_variants[i],
         };''', re.MULTILINE)
 
     print(RE_ARRAY_ITEM)