Model parallel ImageNet parameters.

def mtf_image_transformer_base_imagenet_mp():
  """Model parallel ImageNet parameters."""
  hparams = mtf_image_transformer_base_imagenet()
  hparams.mesh_shape = "model:4;batch:8"
  hparams.layout = "batch:batch;d_ff:model;heads:model"
  hparams.batch_size = 32
  hparams.num_heads = 8
  hparams.d_ff = 8192
  hparams.learning_rate_warmup_steps = 31250
  hparams.unconditional = True
  return hparams