Make DeepEP combine recv do not overlap (#11535)

python/sglang/srt/layers/moe/token_dispatcher/deepep.py

@@ -616,6 +616,9 @@ class _DeepEPDispatcherImplLowLatency(_DeepEPDispatcherImplBase):
         return hidden_states, event, hook, overlap_args
 
     def combine_b(self, hidden_states, event, hook, overlap_args):
+        if overlap_args is not None:
+            overlap_args.stream.wait_stream(self.device_module.current_stream())
+
         hook() if self.return_recv_hook else event.current_stream_wait()
 
         if overlap_args is not None: