mlx_ccb_poll
rv = mlx_ccb_poll(mlx, mc, 10000);
rv = mlx_ccb_poll(mlx, mc, 5000);
rv = mlx_ccb_poll(mlx, mc, MLX_TIMEOUT * 1000);
int mlx_ccb_poll(struct mlx_softc *, struct mlx_ccb *, int);