[SPARK-26073][SQL][FOLLOW-UP] remove invalid comment as we don't use it anymore

## What changes were proposed in this pull request?

remove invalid comment as we don't use it anymore
More details: apache#22976 (comment)

## How was this patch tested?

N/A

Closes apache#23044 from heary-cao/followUpOrdering.

Authored-by: caoxuewen <cao.xuewen@zte.com.cn>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>

Author: heary-cao

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/codegen/GenerateOrdering.scala

@@ -143,8 +143,6 @@ object GenerateOrdering extends CodeGenerator[Seq[SortOrder], Ordering[InternalR
       })
     ctx.currentVars = oldCurrentVars
     ctx.INPUT_ROW = oldInputRow
-    // make sure INPUT_ROW is declared even if splitExpressions
-    // returns an inlined block
     code
   }