hw/ppc/spapr_cpu: Use qdev_is_realized() instead of QOM API

Prefer QDev API for QDev objects, avoid the underlying QOM layer.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Message-Id: <20240216110313.17039-4-philmd@linaro.org>

hw/ppc/spapr_cpu_core.c

@@ -245,8 +245,7 @@ static void spapr_cpu_core_unrealize(DeviceState *dev)
              * spapr_cpu_core_realize(), make sure we only unrealize
              * vCPUs that have already been realized.
              */
-            if (object_property_get_bool(OBJECT(sc->threads[i]), "realized",
-                                         &error_abort)) {
+            if (qdev_is_realized(DEVICE(sc->threads[i]))) {
                 spapr_unrealize_vcpu(sc->threads[i], sc);
             }
             spapr_delete_vcpu(sc->threads[i]);