[Bugfix][ROCm] Fix import error on ROCm

[gshtras]

Fix regression added in #17435
from vllm.vllm_flash_attn.layers.rotary import apply_rotary_emb does not apply to ROCm, it results in

ModuleNotFoundError: No module named 'vllm.vllm_flash_attn.layers'

[github-actions]

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[houseroad]

sorry, my bad..