qom: Have class_init() take a const data argument

Mechanical change using gsed, then style manually adapted
to pass checkpatch.pl script.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20250424194905.82506-4-philmd@linaro.org>
diff --git a/iothread.c b/iothread.c
index 589bcd3..8810376 100644
--- a/iothread.c
+++ b/iothread.c
@@ -292,7 +292,7 @@
     }
 }
 
-static void iothread_class_init(ObjectClass *klass, void *class_data)
+static void iothread_class_init(ObjectClass *klass, const void *class_data)
 {
     EventLoopBaseClass *bc = EVENT_LOOP_BASE_CLASS(klass);