[Sound-open-firmware] tracking work to move SOF app code to Zephyr native interfaces

[Kai Vehmanen]

Hi,

it's been possible for a while to build SOF both with Zephyr [1] and
with the in-tree XTOS version.

We started off by wrapping app calls to OS services into calls to Zephyr. 
Recently, we've started taking the next steps and started replacing the 
main code to use native Zephyr interfaces where appropriate, and wrap the 
calls into XTOS when building with the latter. Intent is to keep both 
builds functional at all times.

Due to the incremental nature, this can be hard to track and understand
at times, so I filed today a meta issue to track all ongoing work:
 - https://github.com/thesofproject/sof/issues/5794

[1]  https://thesofproject.github.io/latest/getting_started/build-guide/build-with-zephyr.html

Br, Kai