Openamp xlnx assist update oct29 2025

[bentheredonethat]

@zeddii please wait on merge

@tnmysh please take a look

this PR

1. preserve backward compatibility
2. enable new driver -- tested in build and boot with latest zynqmp BSP and openamp demo on target

thanks

[zeddii]

Waiting! Will hold for @tnmysh to comment.

[tnmysh]

@bentheredonethat commit message needs to be fixed.

It's not "upstream driver", but "upstream bindings". Please use bindings instead of driver where possible.

[bentheredonethat]

@tnmysh updated.