vdpa_sim: fix vringh initialization in vdpasim_queue_ready()

When we initialize vringh, we should pass the features and the
number of elements in the virtqueue negotiated with the driver,
otherwise operations with vringh may fail.

This was discovered in a case where the driver sets a number of
elements in the virtqueue different from the value returned by
.get_vq_num_max().

In vdpasim_vq_reset() is safe to initialize the vringh with
default values, since the virtqueue will not be used until
vdpasim_queue_ready() is called again.

Fixes: 2c53d0f6

 ("vdpasim: vDPA device simulator")
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20221110141335.62171-1-sgarzare@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Eugenio Pérez <eperezma@redhat.com>