Fix Reshape check (#16349)
### Fix Reshape check
3D->2D reshape by merging the first dims.
There is a bug for the case.
```mermaid
stateDiagram
[768,12,64] --> Reshape
(—1,768) --> Reshape
Reshape --> [768,768]
```
The Reshape pass the upstream Reshape check, but it should not.
### Motivation and Context
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