[quant][fx2trt] Enable comparison with implicit quant mode (#65043)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/65043
Currently got following result, will take a look at the executed graph again:
```
trt fp16 time (ms/iter) 1.0483217239379883
trt int8 time (ms/iter) 0.5329632759094238
trt implicit int8 time (ms/iter) 0.6769704818725586
PyTorch time (ms/iter) 6.453146934509277
```
Test Plan:
```
python torch/fx/experimental/fx2trt/example/quantized_resnet_test.py
```
Imported from OSS
Reviewed By: 842974287
Differential Revision: D30954871
fbshipit-source-id: 8d7ff82b8f5d0b7946fbd38a7cddede7d40b28aa
