Small single parameters.

def mtf_resnet_base_single():
  """Small single parameters."""
  hparams = mtf_resnet_base()
  hparams.num_layers = 6
  hparams.filter_size = 256
  hparams.block_length = 128
  hparams.mesh_shape = ""
  hparams.layout = ""
  return hparams