Fix TryConvertTensorToBroadcastScalar build break (#18497)
### Description
Fix TryConvertTensorToBroadcastScalar build break, caused by incorrect
method call.
- else if (!IsCpuData())
+ else if (!constExpTensor->IsCpuData())
### Motivation and Context
Previous build causing build break.
Co-authored-by: Christian Larson <28911437+chrilaMSFT@users.noreply.github.com>
