vdpa_sim: not reset state in vdpasim_queue_ready

vdpa_sim: not reset state in vdpasim_queue_ready

vdpasim_queue_ready calls vringh_init_iotlb, which resets split indexes.
But it can be called after setting a ring base with
vdpasim_set_vq_state.

Fix it by stashing them. They're still resetted in vdpasim_vq_reset.

This was discovered and tested live migrating the vdpa_sim_net device.

Fixes: 2c53d0f64c06 ("vdpasim: vDPA device simulator")
Signed-off-by: Eugenio Pérez <[email protected]>
Message-Id: <20230118164359.1523760[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>
Acked-by: Jason Wang <[email protected]>
Tested-by: Lei Yang <[email protected]>