virtio_ring: split: Operators use unified style

The operators of vring_alloc_queue_split should use the unified style.Add
space for the '|' ,make it be looked more pretty.

Signed-off-by: Deming Wang <wangdeming@inspur.com>
Message-Id: <20220926022202.1516-1-wangdeming@inspur.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>