Do not use deprecated method in openni_mls_smoothing app
Do not use deprecated method in openni_mls_smoothing app

PR #1960 deprecated `setPolynomialFit()` but did not update the
openni_mls_smoothing app.

drmateo/pcl,drmateo/pcl,drmateo/pcl,drmateo/pcl,drmateo/pcl