hw/misc/xlnx-versal-trng: Free s->prng in finalize, not unrealize

The TYPE_XLNX_VERSAL_TRNG device creates s->prng with g_rand_new()
in its init method, but it frees it in its unrealize method. This
results in a leak in the QOM introspection "initialize-inspect-finalize"
lifecycle:

Direct leak of 2500 byte(s) in 1 object(s) allocated from:
    #0 0x55ec89eae9d8 in __interceptor_calloc (/mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/asan/qemu-system-aarch64+0x294d9d8) (BuildId: 6d5
08874816cc47d17c8dd775e8f809ae520e8cb)
    #1 0x7f697018fc50 in g_malloc0 debian/build/deb/../../../glib/gmem.c:161:13
    #2 0x7f6970197738 in g_rand_new_with_seed_array debian/build/deb/../../../glib/grand.c:202:17
    #3 0x7f6970197816 in g_rand_new debian/build/deb/../../../glib/grand.c:286:10
    #4 0x55ec8aa3656a in trng_init hw/misc/xlnx-versal-trng.c:624:15
    #5 0x55ec8ce75da1 in object_init_with_type qom/object.c:420:9
    #6 0x55ec8ce5d07b in object_initialize_with_type qom/object.c:562:5
    #7 0x55ec8ce5e91d in object_new_with_type qom/object.c:782:5
    #8 0x55ec8ce5e9f1 in object_new qom/object.c:797:12
    #9 0x55ec8d65c81d in qmp_device_list_properties qom/qom-qmp-cmds.c:144:11

Move the free to finalize so it matches where we are initing
s->prng. Since that's the only thing our unrealize method was
doing, this essentially switches the whole function to be
a finalize implementation.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@amd.com>
Reviewed-by: Francisco Iglesias <francisco.iglesias@amd.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20240822162127.705879-3-peter.maydell@linaro.org

hw/misc/xlnx-versal-trng.c

@@ -624,9 +624,9 @@ static void trng_init(Object *obj)
     s->prng = g_rand_new();
 }
 
-static void trng_unrealize(DeviceState *dev)
+static void trng_finalize(Object *obj)
 {
-    XlnxVersalTRng *s = XLNX_VERSAL_TRNG(dev);
+    XlnxVersalTRng *s = XLNX_VERSAL_TRNG(obj);
 
     g_rand_free(s->prng);
     s->prng = NULL;
@@ -689,7 +689,6 @@ static void trng_class_init(ObjectClass *klass, void *data)
     ResettableClass *rc = RESETTABLE_CLASS(klass);
 
     dc->vmsd = &vmstate_trng;
-    dc->unrealize = trng_unrealize;
     rc->phases.hold = trng_reset_hold;
 
     /* Clone uint64 property with set allowed after realized */
@@ -706,6 +705,7 @@ static const TypeInfo trng_info = {
     .instance_size = sizeof(XlnxVersalTRng),
     .class_init    = trng_class_init,
     .instance_init = trng_init,
+    .instance_finalize = trng_finalize,
 };
 
 static void trng_register_types(void)