zephyr: stop using CONFIG_SOF to identify Zephyr build

[kv2019i]

Prepare for change in Zephyr to drop SOF module from the upstream Zephyr manifest. Remove use of CONFIG_SOF which is defined in work/zephyr/modules/Kconfig.sof, but will now be removed.

Fix this by using CONFIG_ZEPHYR_SOF_MODULE instead. This is defined by the Zephyr build system when using the work/sof/west.yml for building SOF. If SOF is built without Zephyr (e.g. testbench or cmocka build), this define will not be set.

After this change, one must use the SOF work/sof/west.yml manifest to build SOF with Zephyr. This is used by all public instructions and CI jobs already.

[Copilot]

Pull Request Overview

This PR removes the dependency on CONFIG_SOF (which was defined in Zephyr's SOF module Kconfig) and replaces it with CONFIG_ZEPHYR_SOF_MODULE. This change prepares for the removal of the SOF module from the upstream Zephyr manifest.

Key changes:

• Replaced CONFIG_SOF with CONFIG_ZEPHYR_SOF_MODULE in CMakeLists.txt
• Removed if SOF wrapper from Kconfig file
• Removed CONFIG_SOF=y setting from app/prj.conf

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
zephyr/Kconfig	Removed the conditional if SOF wrapper around SOF configuration options
zephyr/CMakeLists.txt	Updated build condition from CONFIG_SOF to CONFIG_ZEPHYR_SOF_MODULE
app/prj.conf	Removed explicit CONFIG_SOF=y setting as it's no longer needed

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[kv2019i]

@nashif Alternative to #10321 . It should be possible to merge this already now, in preparation of your PR. Only side-effect that after we merge this in SOF, then SOF cannot be used with Zephyr manifest anymore (but that's anyways happening in Zephyr 97946).

[lgirdwood]

@kv2019i some build issue in CI, do we need any CI changes ?

[kv2019i]

There are issues with this still. I can't really fully explain what happens. Some CONFIG_FOO options are missing when other settings (defined in same Kconfig file) are present. E.g.

.config for MTL build:

# CONFIG_MT8196 is not set
CONFIG_MAX_CORE_COUNT=3
CONFIG_INTEL=y
CONFIG_ACE=y
CONFIG_ACE_VERSION_1_5=y

So CONFIG_MAX_CORE_COUNT is set but not CONFG_CORE_COUNT, both Kconfig options defined in the smae file. Hmm. Will debug this more.

[kv2019i]

Ok, wow, it seems this this the extra CONFIG_CORE_COUNT definition in arch/host now. I now start to realize why nobody else has cleaned this up. This is quite messed up. Let me put this to draft and try to push this commit together with #10334 .

[kv2019i]

See dependencies in #10334 (comment) . PRs #10334 and #10319 need to be merged first, before this PR can go in.