[SPARK-17464][SPARKR][ML] SparkR spark.als argument reg should be 0.1 by default.

## What changes were proposed in this pull request?
SparkR ```spark.als``` arguments ```reg``` should be 0.1 by default, which need to be consistent with ML.

## How was this patch tested?
Existing tests.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #15021 from yanboliang/spark-17464.

R/pkg/R/mllib.R

@@ -1241,7 +1241,7 @@ setMethod("predict", signature(object = "GaussianMixtureModel"),
 #' @note spark.als since 2.1.0
 setMethod("spark.als", signature(data = "SparkDataFrame"),
           function(data, ratingCol = "rating", userCol = "user", itemCol = "item",
-                   rank = 10, reg = 1.0, maxIter = 10, nonnegative = FALSE,
+                   rank = 10, reg = 0.1, maxIter = 10, nonnegative = FALSE,
                    implicitPrefs = FALSE, alpha = 1.0, numUserBlocks = 10, numItemBlocks = 10,
                    checkpointInterval = 10, seed = 0) {