!9453 fix symmetric bug

From: @xiaoyisd
Reviewed-by: @liangchenghui,@jjfeing
Signed-off-by: @liangchenghui

model_zoo/official/cv/mobilenetv2_quant/train.py

@@ -164,7 +164,7 @@ def train_on_gpu():
     # convert fusion network to quantization aware network
     quantizer = QuantizationAwareTraining(bn_fold=True,
                                           per_channel=[True, False],
-                                          symmetric=[True, False],
+                                          symmetric=[False, False],
                                           freeze_bn=1000000,
                                           quant_delay=step_size * 2)
     network = quantizer.quantize(network)