[BugFix] Update draft model TP size check to allow matching target TP size (#9394)

Co-authored-by: Baoyuan Qi <qibaoyuan@126.com>

vllm/config.py

@@ -1408,11 +1408,11 @@ class SpeculativeConfig:
             else:
                 speculative_draft_tensor_parallel_size = \
                     target_parallel_config.tensor_parallel_size
-        elif speculative_draft_tensor_parallel_size != 1:
-            # TODO(wooyeon): allow tp values larger than 1
+        elif speculative_draft_tensor_parallel_size not in (
+                1, target_parallel_config.tensor_parallel_size):
             raise ValueError(
                 f"{speculative_draft_tensor_parallel_size=} cannot be "
-                f"other value than 1")
+                f"other value than 1 or target model tensor_parallel_size")
 
         draft_parallel_config = ParallelConfig(
             pipeline_parallel_size=target_parallel_config.