[SPARK-9913] [MLLIB] LDAUtils should be private

feynmanliang

Author: Xiangrui Meng <meng@databricks.com>

Closes #8142 from mengxr/SPARK-9913.

mllib/src/main/scala/org/apache/spark/mllib/clustering/LDAUtils.scala

@@ -22,7 +22,7 @@ import breeze.numerics._
 /**
  * Utility methods for LDA.
  */
-object LDAUtils {
+private[clustering] object LDAUtils {
   /**
    * Log Sum Exp with overflow protection using the identity:
    * For any a: \log \sum_{n=1}^N \exp\{x_n\} = a + \log \sum_{n=1}^N \exp\{x_n - a\}