[SPARK-19389][ML][PYTHON][DOC] Minor doc fixes for ML Python Params and LinearSVC

## What changes were proposed in this pull request?

* Removed Since tags in Python Params since they are inherited by other classes
* Fixed doc links for LinearSVC

## How was this patch tested?

* doc tests
* generating docs locally and checking manually

Author: Joseph K. Bradley <joseph@databricks.com>

Closes #16723 from jkbradley/pyparam-fix-doc.