[SPARK-14971][ML][PYSPARK] PySpark ML Params setter code clean up

## What changes were proposed in this pull request?
PySpark ML Params setter code clean up.
For examples,
```setInputCol``` can be simplified from
```
self._set(inputCol=value)
return self
```
to:
```
return self._set(inputCol=value)
```
This is a pretty big sweeps, and we cleaned wherever possible.
## How was this patch tested?
Exist unit tests.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #12749 from yanboliang/spark-14971.

1 files changed, 2 insertions, 4 deletions

diff --git a/python/pyspark/ml/tuning.py b/python/pyspark/ml/tuning.py
index eb1f029ebb..b21cf92559 100644
--- a/python/pyspark/ml/tuning.py
+++ b/python/pyspark/ml/tuning.py
@@ -198,8 +198,7 @@ class CrossValidator(Estimator, ValidatorParams):
         """
         Sets the value of :py:attr:`numFolds`.
         """
-        self._set(numFolds=value)
-        return self
+        return self._set(numFolds=value)
 
     @since("1.4.0")
     def getNumFolds(self):
@@ -350,8 +349,7 @@ class TrainValidationSplit(Estimator, ValidatorParams):
         """
         Sets the value of :py:attr:`trainRatio`.
         """
-        self._set(trainRatio=value)
-        return self
+        return self._set(trainRatio=value)
 
     @since("2.0.0")
     def getTrainRatio(self):