!4880 GPU modelzoo change Resnet50 default training to Mixprecision

Merge pull request !4880 from VectorSL/model-zoo

model_zoo/official/cv/resnet/scripts/run_distribute_train_gpu.sh

@@ -55,7 +55,7 @@ then
 fi
 
 
-if [ ! -d $PATH2 ]
+if [ ! -d $PATH1 ]
 then 
     echo "error: DATASET_PATH=$PATH1 is not a directory"
 exit 1

model_zoo/official/cv/resnet/train.py

@@ -163,7 +163,7 @@ if __name__ == '__main__':
             loss = SoftmaxCrossEntropyWithLogits(sparse=True, reduction="mean", is_grad=False,
                                                  num_classes=config.class_num)
 
-        if args_opt.net == "resnet101":
+        if args_opt.net == "resnet101" or args_opt.net == "resnet50":
             opt = Momentum(filter(lambda x: x.requires_grad, net.get_parameters()), lr, config.momentum, config.weight_decay,
                            config.loss_scale)
             loss_scale = FixedLossScaleManager(config.loss_scale, drop_overflow_update=False)