[mlf][efficiency] modify equalization scale operator to return single output (#46449)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/46449
modifies `ComputeEqualizationScale` to have a single output `S`
Test Plan:
```
buck test caffe2/caffe2/quantization/server:compute_equalization_scale_test
```
plus e2e tests
Reviewed By: hx89
Differential Revision: D23946768
fbshipit-source-id: 137c2d7a58bb858db411248606a5784b8066ab23
