Fix converge issue in Orca TF Estimator (#3107)
Fix converge issue in Orca TF Estimator (#3107)

* fix tfdataset standardlize

* update

* fix test

* fix style
yangw1234/BigDL,intel-analytics/BigDL,yangw1234/BigDL,intel-analytics/BigDL,intel-analytics/BigDL,yangw1234/BigDL,yangw1234/BigDL,intel-analytics/BigDL