Update base hparams for tpu
Update base hparams for tpu

PiperOrigin-RevId: 195761510

tensorflow/tensor2tensor,vthorsteinsson/tensor2tensor,tensorflow/tensor2tensor,vthorsteinsson/tensor2tensor,vthorsteinsson/tensor2tensor,tensorflow/tensor2tensor,vthorsteinsson/tensor2tensor,tensorflow/tensor2tensor,tensorflow/tensor2tensor