pds_vdpa: clear config callback when status goes to 0

If the client driver is setting status to 0, something is
getting shutdown and possibly removed.  Make sure we clear
the config_cb so that it doesn't end up crashing when
trying to call a bogus callback.
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Message-Id: <20231110221802.46841-3-shannon.nelson@amd.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

drivers/vdpa/pds/vdpa_dev.c

@@ -461,8 +461,10 @@ static void pds_vdpa_set_status(struct vdpa_device *vdpa_dev, u8 status)
 
 	pds_vdpa_cmd_set_status(pdsv, status);
 
-	/* Note: still working with FW on the need for this reset cmd */
 	if (status == 0) {
+		struct vdpa_callback null_cb = { };
+
+		pds_vdpa_set_config_cb(vdpa_dev, &null_cb);
 		pds_vdpa_cmd_reset(pdsv);
 
 		for (i = 0; i < pdsv->num_vqs; i++) {