Fix tx pkt received counter in hw agent

Summary: The tx pkt receive count was not getting incremented

Reviewed By: shri-khare

Differential Revision: D67827219

fbshipit-source-id: 86555dff82fa3fa08f3cec846b28d181c92e97de

fboss/agent/mnpu/SplitAgentThriftSyncerClient.cpp

@@ -288,6 +288,7 @@ folly::coro::Task<void> ThriftStreamClient<StreamObjectT>::serveStream() {
     }
     auto eventObj = *event;
     eventHandlerFn_(eventObj, hw_);
+    eventReceivedCount_.add(1);
   }
   co_return;
 }