!15748 Fix env error in mobilentv1

From: @c_34
Reviewed-by: @linqingke,@wuxuejian
Signed-off-by: @linqingke

model_zoo/official/cv/mobilenetv1/train.py

@@ -61,7 +61,7 @@ if __name__ == '__main__':
     context.set_context(mode=context.GRAPH_MODE, device_target=target, save_graphs=False)
     if args_opt.parameter_server:
         context.set_ps_context(enable_ps=True)
-    device_id = int(os.getenv('DEVICE_ID'), '0')
+    device_id = int(os.getenv('DEVICE_ID', '0'))
     if args_opt.run_distribute:
         if target == "Ascend":
             context.set_context(device_id=device_id, enable_auto_mixed_precision=True)