[mlir][sparse][NFC] Switch InitOp to bufferization::AllocTensorOp

Now that we have an AllocTensorOp (previously InitTensorOp) in the bufferization dialect, the InitOp in the sparse dialect is no longer needed.

Differential Revision: https://reviews.llvm.org/D126180

mlir/lib/Dialect/SparseTensor/Transforms/SparseTensorPasses.cpp

@@ -119,6 +119,7 @@ struct SparseTensorConversionPass
     target
         .addLegalDialect<bufferization::BufferizationDialect, LLVM::LLVMDialect,
                          memref::MemRefDialect, scf::SCFDialect>();
+    target.addIllegalOp<bufferization::AllocTensorOp>();
     // Translate strategy flags to strategy options.
     SparseTensorConversionOptions options(
         sparseToSparseConversionStrategy(sparseToSparse));