Transition to Zephyr Cmake style in SOF

[kv2019i]

SOF has not had written down style on CMakeFile.txt syntax. The style varies a bit from file to file, creating problems with consistency.

I propose we align SOF CMakeFile.txt files to Zephyr:
https://docs.zephyrproject.org/latest/contribute/style/cmake.html

This can be done incrementally as new files are added.

[kv2019i]

Example PR using this style for new cmake files: #9901

[kv2019i]

The Zephyr style also matches the Cmake projects' own documentation:
https://cmake.org/cmake/help/book/mastering-cmake/cmake/Help/guide/tutorial/index.html

Although it is not an official spec. Here's one example discussion about trying to make it more official:
https://discourse.cmake.org/t/feature-request-universal-enforcement-of-cmake-script-formatting/4852/4