spapr: fix memory leak in spapr_core_pre_plug()

In case of error, we must ensure the dynamically allocated base_core_type
is freed, like it is done everywhere else in this function.

This is a regression introduced in QEMU 2.9 by commit 8149e299.
Signed-off-by: NGreg Kurz <groug@kaod.org>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>

hw/ppc/spapr.c

@@ -3150,9 +3150,9 @@ static void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
      * total vcpus not a multiple of threads-per-core.
      */
     if (mc->has_hotpluggable_cpus && (cc->nr_threads != smp_threads)) {
-        error_setg(errp, "invalid nr-threads %d, must be %d",
+        error_setg(&local_err, "invalid nr-threads %d, must be %d",
                    cc->nr_threads, smp_threads);
-        return;
+        goto out;
     }
 
     core_slot = spapr_find_cpu_slot(MACHINE(hotplug_dev), cc->core_id, &index);