Onnx support: add pos parameter to softmax (#2933)
Onnx support: add pos parameter to softmax (#2933)

* add pos parameter to softmax

* add pos parameter to softmax

* add pos parameter to softmax

* fix review problem

* fix review problem

intel-analytics/BigDL,yangw1234/BigDL,yangw1234/BigDL,intel-analytics/BigDL,intel-analytics/BigDL,yangw1234/BigDL,yangw1234/BigDL,intel-analytics/BigDL