fx quant: add quantized Softmax workflow integration (#75106)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/75106
In https://github.com/pytorch/pytorch/pull/75017 a quantized softmax
kernel was added. This PR adds the FX graph mode quantization workflow
integration to swap `nn.Softmax` to `nnq.Softmax`.
Test Plan:
```
python test/test_quantization.py TestQuantizeFxOps.test_fixed_qparams_ops
```
Reviewed By: kimishpatel, andrewor14
Differential Revision: D35324817
Pulled By: vkuzo
fbshipit-source-id: 710ae3bedf8a6ad1dc411cd9808fdd0ce743e757
(cherry picked from commit d67603c0fbb1d3469d97bd538cec38aa8b03324b)
