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/backends/rng-builtin.c b/backends/rng-builtin.c
index 4cfa7e5..41b7bfa 100644
--- a/backends/rng-builtin.c
+++ b/backends/rng-builtin.c
@@ -55,7 +55,7 @@
     qemu_bh_delete(s->bh);
 }
 
-static void rng_builtin_class_init(ObjectClass *klass, void *data)
+static void rng_builtin_class_init(ObjectClass *klass, const void *data)
 {
     RngBackendClass *rbc = RNG_BACKEND_CLASS(klass);