[Quant][fx][bc-breaking] Do not move models to CPU in convert (#80555)
Summary: Previously, we automatically moved the model to CPU in
torch.ao.quantization.fx.convert to work around the issue where
certain functions called by convert expect CPU arguments. This
commit pushes this responsibility to the caller since it is the
user's decision of which device to use.
Test Plan:
python test/test_quantization.py TestQuantizeFx
python test/test_quantization.py TestQuantizeFxOps
BC-breaking Notes:
Before:
```
model = resnet18(...)
model = prepare_fx(model, qconfig_mapping, example_inputs)
... # calibrate
model = convert_fx(model)
```
After:
```
model = resnet18(...)
model.cpu()
model = prepare_fx(model, qconfig_mapping, example_inputs)
... # calibrate
model = convert_fx(model)
```
Reviewers: jerryzh168
Subscribers: jerryzh168
Differential Revision: [D37528830](https://our.internmc.facebook.com/intern/diff/D37528830)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/80555
Approved by: https://github.com/jerryzh168
