message: Fix a subtle bug that the MLIR function name for the entry point is not "main".
  According to the function comment, the entry point in TFLite is always the first subgraph and the entry point in MLIR is always the "main" function. Thus, update the logic accordingly.
diff: @@ -919,16 +919,14 @@ StatusOr<FuncOp> ConvertSubgraph(
  // represents TFLite, this entry point must be called "main"
  // TODO(b/131175224,b/132239787) Support multiple entry points
  std::string SubgraphName(unsigned index, const tflite::SubGraphT& subgraph) {
  - if (subgraph.name.empty()) {
  if (index == 0) {
  return "main";
  - } else {
  + }
  + if (subgraph.name.empty()) {
  return llvm::formatv("fn_{0}", index).str();
  }
  - } else {
  return subgraph.name;
  }
  -}
  } // namespace
  OwningModuleRef tflite::FlatBufferToMlir(
  