Change dper3 loss module to match dper2 (#28265)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/28265
Fix the difference in dper3 and dper2 when regressionLoss is used.
Test Plan:
test using dper2 model id f134632386
Comparison tool output before change:
```
FOUND OP DIFFERENT WITH DPER2!!!
OP is of type ExpandDims
OP inputs ['supervision:label']
OP outputs ['sparse_nn/regression_loss/mean_squared_error_loss/ExpandDims:0']
===============================
Finished all dper3 ops, number of good ops 11, bad ops 1, skipped 26
run_comparison for dper2 / dper3 nets running time: 0.0020143985748291016
result type: <class 'NoneType'> result: None
```
After change:
```
FOUND OP DIFFERENT WITH DPER2!!!
OP is of type ExpandDims
OP inputs ['sparse_nn_2/regression_loss_2/mean_squared_error_loss_8/Squeeze:0_grad']
OP outputs ['sparse_nn_2/over_arch_2/linear_2/FC_grad']
===============================
Finished all dper3 ops, number of good ops 19, bad ops 1, skipped 16
run_comparison for dper2 / dper3 nets running time: 0.0017991065979003906
result type: <class 'NoneType'> result: None
```
dper2 label part of net P111794577
dper3 label part of net after change P116817194
Reviewed By: kennyhorror
Differential Revision: D17795740
fbshipit-source-id: 9faf96f5140f5a1efdf2985820bda3ca400f61fa
