[Bugfix] EAGLE output norm bug (#14464)

Signed-off-by: Bryan Lu <yuzhelu@amazon.com>

vllm/engine/llm_engine.py

@@ -853,6 +853,10 @@ class LLMEngine:
             self.generation_config_fields, seq.eos_token_id)
 
         # Create the sequence group.
+        draft_size = 1
+        if self.vllm_config.speculative_config is not None:
+            draft_size = \
+                self.vllm_config.speculative_config.num_speculative_tokens + 1
         seq_group = SequenceGroup(
             request_id=request_id,
             seqs=[seq],
@@ -862,7 +866,8 @@ class LLMEngine:
             trace_headers=trace_headers,
             prompt_adapter_request=prompt_adapter_request,
             encoder_seq=encoder_seq,
-            priority=priority)
+            priority=priority,
+            draft_size=draft_size)
 
         return seq_group