[MOE Refactor] Remove QuantType in prepare_finalize.py (#6534)

### What this PR does / why we need it?
To prevent confusion between different QuantType classes, we remove**
QuantType in prepare_finalize.py

- vLLM version: v0.15.0
- vLLM main: https://github.com/vllm-project/vllm/commit/v0.15.0

Signed-off-by: shenchuxiaofugui <1311027364@qq.com>

vllm_ascend/ops/fused_moe/moe_comm_method.py

@@ -30,7 +30,6 @@ from vllm_ascend.ops.fused_moe.prepare_finalize import (
     PrepareAndFinalizeWithAll2All,
     PrepareAndFinalizeWithAllGather,
     PrepareAndFinalizeWithMC2,
-    QuantType,
 )
 from vllm_ascend.ops.fused_moe.token_dispatcher import (
     MoETokenDispatcher,
@@ -38,6 +37,7 @@ from vllm_ascend.ops.fused_moe.token_dispatcher import (
     TokenDispatcherWithAllGather,
     TokenDispatcherWithMC2,
 )
+from vllm_ascend.quantization.methods.base import QuantType
 
 _MoECommMethods: dict[MoECommType | None, MoECommMethod] = {}