bugfix for mtp with multistream_moe (#3419)

### What this PR does / why we need it?
when infer deepseek mtp layer with multistream_moe, we should pass a
boolean to evaluate this feature and fix bugs when we are in mtp layer

- vLLM version: v0.11.0rc3
- vLLM main: https://github.com/vllm-project/vllm/commit/v0.11.0

---------

Signed-off-by: zouyida2052 <zouyida2002@gmail.com>

vllm_ascend/torchair/models/torchair_deepseek_v2.py

@@ -975,7 +975,7 @@ class TorchairDeepseekV2DecoderLayer(DeepseekV2DecoderLayer):
                 # to save npu memory because they're no longer used.
                 dispose_tensor(previous_hidden_states)
                 dispose_tensor(previous_residual)
-        if mla_moe_communication and self.layer_idx > self.first_k_dense_replace:
+        if mla_moe_communication and self.layer_idx > self.first_k_dense_replace and self.layer_idx < self.layers:
             hidden_states = tensor_model_parallel_all_gather(hidden_states,
                                                              dim=0)
 
@@ -1034,7 +1034,7 @@ class TorchairDeepseekV2DecoderLayer(DeepseekV2DecoderLayer):
             # The scaling of DeepseekV2MOE output would be done in the forward
             # of DeepseekV2MOE
             hidden_states *= 1. / self.routed_scaling_factor
-        if mla_moe_communication and self.layer_idx == self.layers - 1:
+        if mla_moe_communication and self.layer_idx >= self.layers - 1:
             hidden_states = tensor_model_parallel_all_gather(hidden_states,
                                                              dim=0)
             residual = tensor_model_parallel_all_gather(residual, dim=0)