spapr: introduce machine unplug handler

We'll be handling unplug of e.g. CPUs and PCDIMMs  via the general
hotplug handler soon, so let's add that handler function.
Acked-by: NDavid Gibson <david@gibson.dropbear.id.au>
Reviewed-by: NGreg Kurz <groug@kaod.org>
Signed-off-by: NDavid Hildenbrand <david@redhat.com>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>

hw/ppc/spapr.c

@@ -3584,6 +3584,11 @@ static void spapr_machine_device_plug(HotplugHandler *hotplug_dev,
     }
 }
 
+static void spapr_machine_device_unplug(HotplugHandler *hotplug_dev,
+                                        DeviceState *dev, Error **errp)
+{
+}
+
 static void spapr_machine_device_unplug_request(HotplugHandler *hotplug_dev,
                                                 DeviceState *dev, Error **errp)
 {
@@ -3978,6 +3983,7 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data)
     mc->get_default_cpu_node_id = spapr_get_default_cpu_node_id;
     mc->possible_cpu_arch_ids = spapr_possible_cpu_arch_ids;
     hc->unplug_request = spapr_machine_device_unplug_request;
+    hc->unplug = spapr_machine_device_unplug;
 
     smc->dr_lmb_enabled = true;
     mc->default_cpu_type = POWERPC_CPU_TYPE_NAME("power8_v2.0");