Since the "bootindex" property is a QOM property and not a qdev property
now, we must alias it explicitly for virtio-blk-pci, as well as CCW and
s390-virtio.

Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>