add operation list for AutocastCPU (#63534)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/63534
In this PR:
* We have changed the default dtype of `AutocastCPU` from `float16` to `bfloat16` as discussed here `https://github.com/pytorch/pytorch/pull/61002`
* We also update the operation list which needs casting to `lower_precision_fp` or `float32`.
Test Plan: Imported from OSS
Reviewed By: zou3519
Differential Revision: D30644914
Pulled By: ezyang
fbshipit-source-id: 8b93485ba452b3759611e3f0ac88e920fe495ac1
