Refactor: adjust NNIConverter API

nn_meter/ir_converters/torch_converter/__init__.py

@@ -1,3 +1,3 @@
 # Copyright (c) Microsoft Corporation.
 # Licensed under the MIT license.
-from .converter import OnnxBasedTorchConverter, NNIBasedTorchConverter
+from .converter import OnnxBasedTorchConverter, NNIBasedTorchConverter, NNIIRConverter

nn_meter/ir_converters/utils.py

@@ -5,8 +5,7 @@ import logging
 from nn_meter.utils.utils import try_import_onnx, try_import_torch, try_import_torchvision_models
 from .onnx_converter import OnnxConverter
 from .frozenpb_converter import FrozenPbConverter
-from .torch_converter import NNIBasedTorchConverter, OnnxBasedTorchConverter
-from .torch_converter.converter import NNIIRConverter
+from .torch_converter import NNIBasedTorchConverter, OnnxBasedTorchConverter, NNIIRConverter
 
 def model_file_to_graph(filename: str, model_type: str, input_shape=(1, 3, 224, 224), apply_nni=False):
     """