s390x/virtio-ccw: fix vhost-scsi intialization

The vhost-scsi-ccw backend is of type VHostSCSICcw, not VirtIOSCSICcw.

This fixes a segfault when invoking

    qemu-system-s390x -device vhost-scsi-ccw,?
Reviewed-by: NThomas Huth <thuth@linux.vnet.ibm.com>
Tested-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>

hw/s390x/virtio-ccw.c

@@ -1528,7 +1528,7 @@ static void vhost_ccw_scsi_class_init(ObjectClass *klass, void *data)
 static const TypeInfo vhost_ccw_scsi = {
     .name          = TYPE_VHOST_SCSI_CCW,
     .parent        = TYPE_VIRTIO_CCW_DEVICE,
-    .instance_size = sizeof(VirtIOSCSICcw),
+    .instance_size = sizeof(VHostSCSICcw),
     .instance_init = vhost_ccw_scsi_instance_init,
     .class_init    = vhost_ccw_scsi_class_init,
 };