[mlir][Tensor] Make TilingInterface implementation only return hand…

…le to the created `pad` operation.

Pad tiling implementation only needs to return the tiled pad
operation. The rest of the generated code is related to handling
boundary conditions.

Reviewed By: hanchung

Differential Revision: https://reviews.llvm.org/D146439

mlir/lib/Dialect/Tensor/IR/TensorTilingInterfaceImpl.cpp

@@ -648,7 +648,7 @@ FailureOr<TilingResult> tensor::bubbleUpPadSlice(OpBuilder &b,
           elseOp = createPadOfExtractSlice();
           b.create<scf::YieldOp>(loc, castResult(elseOp->getResult(0)));
         });
-    return TilingResult{{result}, SmallVector<Value>(result->getResults())};
+    return TilingResult{{elseOp}, SmallVector<Value>(result->getResults())};
   }
 
   Operation *newPadOp = createPadOfExtractSlice();