[Perf] Dont create unnecessary pooling params (#22876)

Signed-off-by: Lucas Wilkinson <lwilkins@redhat.com>

vllm/v1/worker/gpu_model_runner.py

@@ -341,13 +341,13 @@ class GPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
         model_kwargs = dict[str, Any]()
         num_reqs = self.input_batch.num_reqs
 
-        pooling_params = self.input_batch.pooling_metadata.pooling_params
-
-        num_pooling_reqs = len(pooling_params)
+        num_pooling_reqs = len(self.input_batch.pooling_params)
 
         if num_pooling_reqs == 0:
             return model_kwargs
 
+        pooling_params = self.input_batch.pooling_metadata.pooling_params
+
         assert num_pooling_reqs == num_reqs
 
         token_type_id_requests = dict[int, Any]()