this Node Loop-generic_loop_Loop__42 has no value_infer on SSD-mobilenet-int8

[saurabhtangri]

Describe the bug
A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior:

1. Go to : https://github.com/onnx/models/blob/main/validated/vision/object_detection_segmentation/ssd-mobilenetv1/model/ssd_mobilenet_v1_12-int8.onnx

SSD-MobilenetV1-12-qdq

import onnx_tool
import numpy as np
modelpath = '/home/ssd_mobilenet_v1_13-qdq.onnx'
m = onnx_tool.Model(modelpath)
m.graph.shape_infer({'inputs': np.ones((1,383,640,3), dtype=np.uint8)}) # update tensor shapes with new input tensor
m.graph.profile()
m.graph.print_node_map() # console print

m.save_model('/home/ssd_mobilenet_v1_13-qdq-mods.onnx', shape_only=False) # only with weight tensor shapes and dynamic tensor shapes

5. See error
   NotImplementedError(f'this Node {self.op_type}-{self.name} has no value_infer
   this Node Loop-generic_loop_Loop__42 has no value_infer

Screenshots
If applicable, add screenshots to help explain your problem.

[ThanatosShinji]

it's a known issue that Loop is not supported. But this model is not simplified.

The real model body does not have this Loop node. It should start with this Mul node.