The two common virtio features can be defined per bus, so move all
into bus class device to make code more clean.
As discussed with cornelia, s390-virtio-blk doesn't support
the two features at all, so keep s390-virtio as it.
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> #for s390 ccw
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
MST: rebase and resolve conflicts
85d1277e66