HParams for training ASR model on Librispeech on TPU v1.

def transformer_librispeech_tpu_v1():
  """HParams for training ASR model on Librispeech on TPU v1."""
  hparams = transformer_librispeech_v1()
  update_hparams_for_tpu(hparams)

  hparams.batch_size = 16
  librispeech.set_librispeech_length_hparams(hparams)
  return hparams