enable bf16 emb (#94163)
Merge https://github.com/pytorch/pytorch/pull/89199 and https://github.com/pytorch/pytorch/pull/91949 into one PR.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/94163
Approved by: https://github.com/jianyuh, https://github.com/malfet, https://github.com/jgong5
