message: Avoid variable name conflict in MLIR tutorial code snippet
diff: @@ -270,16 +270,17 @@ types, etc). We can always get an instance of our toy operation by using LLVM's
  casting infrastructure:
  ```c++
  -void processConstantOp(mlir::Operation *op) {
  - ConstantOp op = llvm::dyn_cast<ConstantOp>(op);
  +void processConstantOp(mlir::Operation *operation) {
  + ConstantOp op = llvm::dyn_cast<ConstantOp>(operation);
  // This operation is not an instance of `ConstantOp`.
  if (!op)
  return;
  // Get the internal operation instance back.
  - mlir::Operation *internalOp = op.getOperation();
  - assert(internalOp == op && "these operation instances are the same");
  + mlir::Operation *internalOperation = op.getOperation();
  + assert(internalOperation == operation &&
  + "these operation instances are the same");
  }
  ```
  