Overlay management - reverting to previous logic

[igorpecovnik]

Description

Old armbian config doesn't need changes at build time. It seems all overlays are in the same place except legacy / vendor kernels. We need to look into if exceptions are still needed:

https://github.com/armbian/config/blob/master/debian-config-functions#L58-L61

@wizbandit @stephengraf @The-going

Testing Procedure

• Manual on H3 based hw

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have ensured that my changes do not introduce new warnings or errors
• No new external dependencies are included
• Changes have been tested and verified
• I have included necessary metadata in the code, including associative arrays