[VITISAI] fix compile error for onnxruntime (#17252)

### Description
<!-- Describe your changes. -->
Updated the code to pass in the missing parameter


### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->
Compile error. See https://github.com/microsoft/onnxruntime/issues/17139

Co-authored-by: Yueqing Zhang <yueqingz@amd.com>

onnxruntime/core/providers/vitisai/imp/graph.cc

@@ -138,6 +138,7 @@ void graph_save(const Graph& graph, const std::string& filename, const std::stri
     model_proto = model.ToProto();
   } else {
     model_proto = model.ToGraphProtoWithExternalInitializers(filename_dat,
+                                                             ToPathString(filename),
                                                              initializer_size_threshold);
   }
   auto& metadata = model.MetaData();