UART dataBits property is broken

[kevinmehall]

var tessel = require('tessel')
var port = tessel.port['D'];
var uart = new port.UART({
  dataBits: 8,
});

On master, this fails with Error: Invalid property value: 8 due to tessel/t1-runtime#723. In v0.1.26, it passes an invalid flag value to hw, which hangs the processor.