vdpa: support packed virtqueue for set/get_vq_state()

vdpa: support packed virtqueue for set/get_vq_state()

This patch extends the vdpa_vq_state to support packed virtqueue
state which is basically the device/driver ring wrap counters and the
avail and used index. This will be used for the virito-vdpa support
for the packed virtqueue and the future vhost/vhost-vdpa support for
the packed virtqueue.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210602021536.39525-2-jasowang@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>