Make single thread bench cheat-resistant

Each hash is dependent on the previous hash to make multi-threaded cheating impossible.

src/backend/opencl/OclBackend.cpp

@@ -463,7 +463,7 @@ void xmrig::OclBackend::start(IWorker *worker, bool ready)
     mutex.unlock();
 
     if (ready) {
-        worker->start();
+        worker->start(d_ptr->controller->config());
     }
 }