Fix xnnpack compile error on arm32 (#18291)
### Description
<!-- Describe your changes. -->
Use different march flag to workaround what appears to be a clang issue.
See https://github.com/tensorflow/tensorflow/issues/59970 for links to
various relevant pieces of info/discussions.
### 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. -->
