## What changes were proposed in this pull request?
```ml.R``` example depends on ```e1071``` package, if it's not available in users' environment, it will fail. I think the example should not depends on third-party packages, so I update it to remove the dependency.

## How was this patch tested?
Manual test.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #16548 from yanboliang/spark-19158.

(cherry picked from commit 2c586f50)
Signed-off-by: Yanbo Liang <ybliang8@gmail.com>