[Transformer2DModel] Handle `norm_type` safely while remapping (#8370)
* handle norm_type of transformer2d_model safely.
* log an info when old model class is being returned.
* Apply suggestions from code review
Co-authored-by: Dhruv Nair <dhruv.nair@gmail.com>
* remove extra stuff
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Co-authored-by: Dhruv Nair <dhruv.nair@gmail.com>