[Quant] Refactor handling of FixedQParams operators (#68143)
Summary:
**Summary**: FixedQParams operators do not need fake quantization
in the prepare step. This commit introduces FixedQParamsObserver
and makes FixedQParamsFakeQuantize a simple wrapper around this
observer. It also removes the fake quantize logic in forward.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68143
Test Plan:
Added two tests:
python3 test/test_quantization.py TestQuantizeFx.test_fixed_qparams_patterns
python3 test/test_quantization.py TestQuantizeFx.test_register_patterns
**Reviewers**: Jerry Zhang
**Subscribers**: Jerry Zhang, Supriya Rao
**Tasks**: T104942885
**Tags**: pytorch
Reviewed By: albanD
Differential Revision: D32484427
Pulled By: andrewor14
fbshipit-source-id: 5a048b90eb4da79074c5ceffa3c8153f8d8cd662
