[VITISAI] fix out of bound error on graph with loop (#17065)
### Description
<!-- Describe your changes. -->
Check the bound of the node_get_inputs for out of bound error.
### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->
Model with loop would encounter this error. Currrent we do not support
custom op for loop. So, ideally it would throw an error and fall back to
CPU evalution.