Revert "enable bf16 emb (#94163)"
This reverts commit f3bf46e801dec2637751224fd6e27fbf97453bc6.
Reverted https://github.com/pytorch/pytorch/pull/94163 on behalf of https://github.com/huydhn due to Sorry for reverting your PR. But I suspect that it causes flaky SIGSEGV failure for linux-bionic-py3.8-clang9 / test (crossref) job in trunk. For example, https://hud.pytorch.org/pytorch/pytorch/commit/05397b12505f4fd1bc98af562e103f4162993c1a
