[SPARK-19815][SQL] Not orderable should be applied to right key instead of left key

[zhzhan]

What changes were proposed in this pull request?

Change the orderable condition.

How was this patch tested?

Relies on existing test.

Please review http://spark.apache.org/contributing.html before opening a pull request.

[SparkQA]

Test build #73873 has finished for PR 17155 at commit 91a6165.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[gatorsmile]

Add a test case to https://github.com/apache/spark/blob/master/sql/core/src/test/scala/org/apache/spark/sql/JoinSuite.scala?

[zhzhan]

@gatorsmile Thanks for reviewing this. I am thinking the logic again. On the surface, the logic may be correct. Since in the join, the left and right key should be the same type. Will close the PR.