Use mlir::OpState::operator->() to get to Operation::getAttrs().

This is a preparation step to remove getAttrs() from OpState.

PiperOrigin-RevId: 360159716

lib/Dialect/mhlo/transforms/hlo_legalize_to_lhlo.cc

@@ -424,7 +424,7 @@ struct HloToLhloReduceOpConverter : public BaseOpConversion<mhlo::ReduceOp> {
       buffer_args.push_back(InsertAlloc(loc, result, &rewriter));
     }
     auto new_op = rewriter.create<lmhlo::ReduceOp>(loc, llvm::None, buffer_args,
-                                                   op.getAttrs());
+                                                   op->getAttrs());
 
     // Copy over the operations inside the region.
     rewriter.inlineRegionBefore(op.body(), new_op.body(), new_op.body().end());