[SPARK-13686][MLLIB][STREAMING] Add a constructor parameter `reqParam` to (Streaming)LinearRegressionWithSGD

## What changes were proposed in this pull request?

`LinearRegressionWithSGD` and `StreamingLinearRegressionWithSGD` does not have `regParam` as their constructor arguments. They just depends on GradientDescent's default reqParam values.
To be consistent with other algorithms, we had better add them. The same default value is used.

## How was this patch tested?

Pass the existing unit test.

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #11527 from dongjoon-hyun/SPARK-13686.