[bugfix] Fix moe bug: allgather error. (#3279)

It will crash when deepseek model executed in A2.


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

---------

Signed-off-by: weijinqian_v1 <weijinqian@huawei.com>
Co-authored-by: weijinqian_v1 <weijinqian@huawei.com>

tests/ut/ops/test_token_dispatcher.py

@@ -269,6 +269,7 @@ class TestTokenDispatcherWithAllGather(TestBase):
     def test_token_combine_with_expert_map(self):
         self.dispatcher.expert_map = torch.tensor([0, 1, 2, 3])
         self.dispatcher.sorted_token_indices = torch.tensor([0, 1, 1, 1, 1, 1])
+        self.dispatcher.expanded_row_idx = torch.tensor([0, 1, 1, 1, 1, 1])
         self.dispatcher.sorted_weights = torch.tensor(
             [0.5, 0.5, 0.5, 0.5, 0.5, 0.5])
         self.dispatcher.original_shape = (3, 128)