[FEATURE][Zephyr] Move all hw init code from platform_init() to Zephyr

[kv2019i]

Is your feature request related to a problem? Please describe.
Much of the HW init code is already ignored in Zephyr builds in the Zephyr main() -> sof_main() -> primary_core_init() -> platform_init() code path, but not all. This work should be completed.

Examples like platform_init_hw() must be moved to Zephyr side and not the SOF definition should not be used when building for Zephyr.

This has created multiple problems for unit tests on Zephyr side (like for cAVS SSP driver, FYI @juimonen ).

Update 2023: this doesn't really affect "pure Zephyr" platforms unless we remove platform.h completely, but that's beyond scope of this item. So I filed #7248 to track the general discussion of platform.h fate and let's use this to track existing issues with HW init code in platform_init() or current hybrid platforms:

• remove HW init from Intel cAVS platform

[lenghonglin]

see this #5068 (comment)

[lgirdwood]

Making a v2.2 for Intel platforms. @dbaluta NXP likewise for v2.2 ?

[kv2019i]

@dbaluta I don't see any clear overlap in platform/imx8/platform.c where SOF side platform code would be initializing hw that is already handle in Zephyr. IMX8 interrupt handling is one possible item, but I guess this is not overlapping with Zephyr yet (it's really handled on SOF side). Feel free to yet in the task tracking list.

[lgirdwood]

@juimonen @dbaluta on track for v2.6 ?

[kv2019i]

With #7702 merged, we can now close this.

[kv2019i]

Moving this meta item to v2.8. For v2.7, we completed #7896 and start to be completed for Intel targets.