message: Remove DataTransferOptions
  Summary:
  DataTransferOptions was removed from poplar as it always converts to halfs.
  Fixes T3132
  Test Plan: All tests pass
  Reviewers: davidn
  Maniphest Tasks: T3132
diff: @@ -148,9 +148,6 @@ class EntryVisitor : public FullVisitor {
  module_shapes = FlattenedXlaShape(mod_shape);
  }
  - poplar::DataTransferOptions opt;
  - opt.convertHalf = true;
  -
  for (unsigned i = 0; i < shapes.size(); i++) {
  poplar::Tensor out;
  TF_ASSIGN_OR_RETURN(out, AddTensor(graph_, std::make_pair(inst, i),
  @@ -167,14 +164,14 @@ class EntryVisitor : public FullVisitor {
  if (parameter_streamed[inst->parameter_number()]) {
  auto fifo = graph_.addHostToDeviceFIFO(
  - GetInputCopyHandle(inst->parameter_number(), i),
  - out.elementType(), out.numElements(), opt);
  + GetInputCopyHandle(inst->parameter_number(), i), out.elementType(),
  + out.numElements());
  sequence.add(poplar::program::Copy(fifo, out));
  } else {
  graph_.createHostWrite(GetInputCopyHandle(inst->parameter_number(), i),
  - out, opt);
  + out);
  }
  }
  return Status::OK();
  @@ -183,9 +180,6 @@ class EntryVisitor : public FullVisitor {
  Status FinishVisit(HloInstruction* inst) {
  HloComputation* comp = inst->parent();
  - poplar::DataTransferOptions opt;
  - opt.convertHalf = true;
  -
  auto outputs = FindInstructionOutputs(tensor_map, inst);
  auto* layout = comp->parent()->mutable_host_entry_computation_layout();
  @@ -207,7 +201,7 @@ class EntryVisitor : public FullVisitor {
  if (!output_streamed[o]) {
  poplar::Tensor out = ConvertFromDeviceLayout(shapes[o], outputs[o]);
  - graph_.createHostRead(GetOutputCopyHandle(o), out, opt);
  + graph_.createHostRead(GetOutputCopyHandle(o), out);
  }
  }
  @@ -253,15 +247,11 @@ class EntryVisitor : public FullVisitor {
  poplar::Tensor out =
  ConvertFromDeviceLayout(shapes[index], outputs[o]);
  - poplar::DataTransferOptions opt;
  - opt.convertHalf = true;
  -
  auto fifo = graph_.addDeviceToHostFIFO(
  GetOutputCopyHandle(index), out.elementType(),
  - out.numElements(), opt);
  + out.numElements());
  sequence.add(poplar::program::Copy(out, fifo));
  -
  }
  }
  }
  