fix

ge/engine_manager/dnnengine_manager.cc

@@ -44,7 +44,6 @@ const char *const kAttch = "attach";
 const char *const kVectorCore = "VectorCore";
 const char *const kVectorEngine = "VectorEngine";
 const char *const kAIcoreEngine = "AIcoreEngine";
-const char *const kCustomOpFlag = "_custom_op_flag";
 const char *const kHostCpuEngineName = "DNN_VM_HOST_CPU";
 const char *const kHostCpuOpKernelLibName = "DNN_VM_HOST_CPU_OP_STORE";
 }  // namespace