[cherry-pick pr-4254] bugfix for mtp>1 when lm_head_tp>1 (#4360)

### What this PR does / why we need it?
Previously, the dummy run executed compute_logits only once, regardless
of num_speculative_tokens. This caused execute_model to hang on
compute_logits when lm head tensor parallelism exceeded 1. The fix
ensures compute_logits executes correctly during dummy run, matching
num_speculative_tokens.

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

vllm_ascend/spec_decode/eagle_proposer.py

@@ -116,7 +116,8 @@ class EagleProposer(Proposer):
                   num_reqs: int = 0,
                   num_tokens_across_dp: Optional[torch.Tensor] = None,
                   aclgraph_runtime_mode: CUDAGraphMode = CUDAGraphMode.NONE,
-                  batch_descriptor=None):
+                  batch_descriptor=None,
+                  dummy_compute_logits=lambda hidden_states: None):
         moe_comm_type = self.runner._select_moe_comm_method(
             num_tokens, with_prefill)
         with set_ascend_forward_context(None,
@@ -128,6 +129,7 @@ class EagleProposer(Proposer):
                 positions=self.positions[:num_tokens],
                 hidden_states=self.hidden_states[:num_tokens],
             )
+            dummy_compute_logits(self.hidden_states)
 
     def generate_token_ids(self,
                            valid_sampled_token_ids: list[list[int]],