fix pass and convert_op for preln_ernie and add preln_ernie'flag in pass

Author: Wangzheee

paddle/fluid/inference/analysis/ir_pass_manager.cc

@@ -198,6 +198,7 @@ void IRPassManager::CreatePasses(Argument *argument,
  pass->Set("lite_ops_filter",
  new std::vector<std::string>(argument->lite_ops_filter()));
  pass->Set("predictor_id", new int(argument->predictor_id()));
+ pass->Erase("enable_int8");
  pass->Set("enable_int8", new bool(lite_enable_int8));
  pass->Set("use_gpu", new bool(argument->use_gpu()));
  pass->Set("zero_copy", new bool(argument->lite_zero_copy()));