error: Apply error_propagate_null.cocci again

Signed-off-by: NFam Zheng <famz@redhat.com>
Message-Id: <20170421122710.15373-15-famz@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

hw/i386/pc.c

@@ -1104,9 +1104,7 @@ static void pc_new_cpu(const char *typename, int64_t apic_id, Error **errp)
     object_property_set_bool(cpu, true, "realized", &local_err);
 
     object_unref(cpu);
-    if (local_err) {
-        error_propagate(errp, local_err);
-    }
+    error_propagate(errp, local_err);
 }
 
 void pc_hot_add_cpu(const int64_t id, Error **errp)

hw/s390x/virtio-ccw.c

@@ -1761,9 +1761,7 @@ static void vhost_vsock_ccw_realize(VirtioCcwDevice *ccw_dev, Error **errp)
 
     qdev_set_parent_bus(vdev, BUS(&ccw_dev->bus));
     object_property_set_bool(OBJECT(vdev), true, "realized", &err);
-    if (err) {
-        error_propagate(errp, err);
-    }
+    error_propagate(errp, err);
 }
 
 static void vhost_vsock_ccw_class_init(ObjectClass *klass, void *data)

hw/usb/bus.c

@@ -762,9 +762,7 @@ static void usb_set_attached(Object *obj, bool value, Error **errp)
 
     if (value) {
         usb_device_attach(dev, &err);
-        if (err) {
-            error_propagate(errp, err);
-        }
+        error_propagate(errp, err);
     } else {
         usb_device_detach(dev);
     }