[pytorch] Fix the extra_repr print message for float16 dynamic quantization (#36044)
Summary:
When applying the float16 dynamic quantization with
```
model = torch.quantization.quantize_dynamic(
model, {torch.nn.Linear}, dtype=torch.float16
)
print(model)
```
there is an issue when we try to print the model. Basically we cannot print the `qscheme` information for float16 weight (It is not per-tensor or per-channel quantization defined for int8 dynamic quantization).
Before this PR:
```
Traceback (most recent call last):
File "dlrm_s_pytorch.py", line 860, in <module>
print(dlrm)
File "/home/jianyuhuang/miniconda3/lib/python3.7/site-packages/torch/nn/modules/module.py", line 1142, in __repr__
mod_str = repr(module)
File "/home/jianyuhuang/miniconda3/lib/python3.7/site-packages/torch/nn/modules/module.py", line 1142, in __repr__
mod_str = repr(module)
File "/home/jianyuhuang/miniconda3/lib/python3.7/site-packages/torch/nn/modules/module.py", line 1136, in __repr__
extra_repr = self.extra_repr()
File "/home/jianyuhuang/miniconda3/lib/python3.7/site-packages/torch/nn/quantized/dynamic/modules/linear.py", line 55, in extra_repr
self.in_features, self.out_features, self.weight().qscheme()
RuntimeError: Could not run 'aten::qscheme' with arguments from the 'CPUTensorId' backend. 'aten::qscheme' is only available for these back
ends: [QuantizedCPUTensorId, VariableTensorId].
```
After this PR:
```
(4): DynamicQuantizedLinear(
in_features=2, out_features=1, dtype=torch.float16
(_packed_params): LinearPackedParams()
)
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/36044
Differential Revision: D20860811
Pulled By: jianyuh
fbshipit-source-id: d1405a185f46a8110e6d27982b40534c854f4d1c
