[MINOR] remove dead code in ExpressionEvalHelper

## What changes were proposed in this pull request?

This addresses https://github.com/apache/spark/pull/21236/files#r207078480

both #21236 and #21838 add a InternalRow result check to ExpressionEvalHelper and becomes duplicated.

## How was this patch tested?

N/A

Author: Wenchen Fan <[email protected]>

Closes #21958 from cloud-fan/minor.

Author: cloud-fan

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvalHelper.scala

@@ -105,9 +105,6 @@ trait ExpressionEvalHelper extends GeneratorDrivenPropertyChecks with PlanTestBa
         if (expected.isNaN) result.isNaN else expected == result
       case (result: Float, expected: Float) =>
         if (expected.isNaN) result.isNaN else expected == result
-      case (result: UnsafeRow, expected: GenericInternalRow) =>
-        val structType = exprDataType.asInstanceOf[StructType]
-        result.toSeq(structType) == expected.toSeq(structType)
       case (result: Row, expected: InternalRow) => result.toSeq == expected.toSeq(result.schema)
       case _ =>
         result == expected