[hotfix] Fixed fused layernorm bug without apex (#5609)

* fixed fused layernorm bug without apex

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* same for flash attn

* remove flash attn check

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>