Is your feature request related to a problem? Please describe.
When a software module is added to SOF that can be used both in XTOs and in Zephyr builds, the module sources need to be added to CMake rules twice:

• first in sof/src/foo/CMakeLists.txt (for XTOS), and
• second time to sof/zephyr/CMakeLists.txt (for Zephyr)

This split of Cmake rules dates back to the time when Zephyr support was introduced and codebase was not cleanly split between operating systems. Now we have a cleaner split at top-level source directories, so it should be possible to start cleaning up this overlap in definitions.

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Additional context
Platforms where transition to Zephyr is still in progress might cause some extra challenges to doing this makefile cleanup. E.g. see XTOS-only a

• [FEATURE][Zephyr] Clarify expectations of platform.h for Zephyr SOF builds #7248
• [FEATURE] remove duplicated C files additions in CMake rules for src/audio/ modules #8606