dbr quant overhead[4/x]: speed up hook type calculations (#68351)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68351
Speeds up `get_module_hook_type` and `get_torch_function_hook_type` by
bypassing the expensive `torch.nn.Module` getters and setters and
fetching `_auto_quant_state` directly.
Test Plan:
Model level benchmarking is noisy. Individual `cProfile` results:
```
// MobileNetV2, 1x3x224x224 input, % of time spent by function during DBR convert
// before
get_module_hook_type - 5.96%
get_torch_function_hook_type - 2.24%
// after
get_module_hook_type - 2.10%
get_torch_function_hook_type - 0.57%
```
Reviewed By: jerryzh168
Differential Revision: D32463756
Pulled By: vkuzo
fbshipit-source-id: 6eb199052ddf8d78f1c123a427e7437fc7c4fe58
