Fix warning log in switch order layer

paddle/gserver/layers/SwitchOrderLayer.cpp

@@ -32,10 +32,10 @@ bool SwitchOrderLayer::init(const LayerMap& layerMap,
   outDims_ = TensorShape(4);
 
   auto& reshape_conf = config_.reshape_conf();
-  for (size_t i = 0; i < reshape_conf.heightaxis_size(); i++) {
+  for (int i = 0; i < reshape_conf.heightaxis_size(); i++) {
     heightAxis_.push_back(reshape_conf.heightaxis(i));
   }
-  for (size_t i = 0; i < reshape_conf.widthaxis_size(); i++) {
+  for (int i = 0; i < reshape_conf.widthaxis_size(); i++) {
     widthAxis_.push_back(reshape_conf.widthaxis(i));
   }
   createFunction(nchw2nhwc_, "NCHW2NHWC", FuncConfig());