Fix a Scala style error.

Author: zhangjiajin

mllib/src/test/scala/org/apache/spark/mllib/fpm/PrefixSpanSuite.scala

@@ -102,7 +102,7 @@ class PrefixspanSuite extends SparkFunSuite with MLlibTestSparkContext {
     val expectedValue3 = Array(
       (Array(1), 4L),
       (Array(1, 3), 2L),
-      (Array(1,4), 2L),
+      (Array(1, 4), 2L),
       (Array(1, 5), 2L),
       (Array(2, 1), 2L),
       (Array(2), 2L),