CODEOWNERS: Add maintainers explicitly

[golowanow]

Add maintainers as code owners explicitly to resolve 'unknown owner' error which appears in forks.

[lgirdwood]

@marc-hb if you are still interested pls approve, if not we can remove your name from the PR.

[marc-hb]

Thanks, I don't mind the notifications, there are not that many :-) I will remove myself if that changes.

[marc-hb]

Add maintainers as code owners explicitly to resolve 'unknown owner' error which appears in forks.

The change LGTM but I don't understand and I'm curious about this GitHub error message... could you elaborate and do you have an example you can share?

[golowanow]

I'm curious about this GitHub error message... could you elaborate and do you have an example you can share?

well, an example is this PR itself - currently it shows only the test-maintainers group as the CODEOWNER's owner (and myself as the group member). GH should also show a error here if there is an owner which doesn't exist or have no access to the repo.

[marc-hb]

... to resolve 'unknown owner' error which appears in forks.

GH should also show a error here if ...

These look like two different issues. Nevermind.