Fix conflict between Tutel and top-2 gate in MoE layer (#2053)

* fix conflit between tutel and top-2 gate
Co-authored-by: Ammar Ahmad Awan <ammar.awan@microsoft.com>
Co-authored-by: Jeff Rasley <jerasley@microsoft.com>

deepspeed/moe/sharded_moe.py

@@ -471,13 +471,17 @@ def __init__(self,
         self.timers = SynchronizedWallClockTimer()
         self.wall_clock_breakdown = False
 
-        self.use_tutel = use_tutel and TUTEL_INSTALLED
+        self.use_tutel = use_tutel and TUTEL_INSTALLED and gate.k == 1
 
         if self.use_tutel:
             logger.info('Using Tutel optimizations.')
         elif use_tutel and not TUTEL_INSTALLED:
             logger.warning("Tutel optimization requested but not installed. "
                            "Proceeding without Tutel.")
+        elif use_tutel and TUTEL_INSTALLED and gate.k != 1:
+            logger.warning(
+                "To enable Tutel optimization, use top-1 instead of top-2 gate. "
+                "Proceeding without Tutel.")
 
     def _set_ep_group(self, ep_group):
         self.ep_group = ep_group