[BugFix] Fix import error for fused_moe (#18642)

Signed-off-by: wangxiyuan <[email protected]>

Author: wangxiyuan

vllm/model_executor/layers/fused_moe/layer.py

@@ -41,6 +41,7 @@
         from .pplx_prepare_finalize import PplxPrepareAndFinalize
 else:
     fused_experts = None  # type: ignore
+    FusedMoEPermuteExpertsUnpermute = None  # type: ignore
     FusedMoEPrepareAndFinalize = None  # type: ignore
 if is_rocm_aiter_moe_enabled():
     from vllm.model_executor.layers.fused_moe.rocm_aiter_fused_moe import (  # noqa: E501