[mlir] Fix a warning

This patch fixes:

  mlir/lib/Dialect/Linalg/Transforms/DataLayoutPropagation.cpp:52:42:
  error: 'None' is deprecated: Use std::nullopt
  instead. [-Werror,-Wdeprecated-declarations]

1 files changed, 1 insertions, 1 deletions

diff --git a/mlir/lib/Dialect/Linalg/Transforms/DataLayoutPropagation.cpp b/mlir/lib/Dialect/Linalg/Transforms/DataLayoutPropagation.cpp
index dc132b22c7c9..603faf22cf2d 100644
--- a/mlir/lib/Dialect/Linalg/Transforms/DataLayoutPropagation.cpp
+++ b/mlir/lib/Dialect/Linalg/Transforms/DataLayoutPropagation.cpp
@@ -49,7 +49,7 @@ struct PackInfo {
 static PackInfo getPackingInfoFromConsumer(
     AffineMap indexingMap, ArrayRef<OpFoldResult> innerTileSizes,
     ArrayRef<int64_t> innerDimsPos, ArrayRef<int64_t> outerDimsPerm,
-    Optional<Value> paddingValue = llvm::None) {
+    Optional<Value> paddingValue = std::nullopt) {
   LLVM_DEBUG(
       { llvm::dbgs() << "--- Construct PackInfo From A Consumer ---\n"; });
   PackInfo packInfo;