[mlir][linalg] Fix FusionOnTensors header and make local method static (NFC).

mlir/lib/Dialect/Linalg/Transforms/FusionOnTensors.cpp

-//===- Fusion.cpp - Implementation of linalg Fusion -----------------------===//
+//===- FusionOnTensors.cpp - Implementation of linalg Fusion --------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements linalg fusion on tensors

 // StructuredOp specific helpers.
 //===----------------------------------------------------------------------===//
 
 /// Returns the tiled slice dimensions given the tiled consumer loop dimensions.
 /// The slice defines a hyper rectangular iteration space and fusing the
 /// producer is always possible. However, depending on the consumer indexing
 /// map, not all slice elements may be consumed and the tiles may overlap. In
 /// these cases, fusion introduces redundant computation.
-SmallVector<int64_t> getTiledSliceDims(OpOperand *consumerOperand,
+static SmallVector<int64_t> getTiledSliceDims(OpOperand *consumerOperand,
                                               ArrayRef<int64_t> tiledLoopDims) {
   // Get the consumer operand indexing map.
   LinalgOp consumerOp = consumerOperand->getOwner();
   AffineMap indexingMap = consumerOp.getTiedIndexingMap(consumerOperand);
 
   // Search the slice dimensions tiled by a tile loop dimension.
   DenseSet<int64_t> tiledSliceDims;
   for (auto en : enumerate(indexingMap.getResults())) {
     for (auto tiledLoopDim : tiledLoopDims) {