Draft: Remove PinePhone UCM in favour of upstream

DO NOT MERGE until ALSA UCM tags a new release containing https://github.com/alsa-project/alsa-ucm-conf/commit/93d514761c699028fd2e8c8da86901cf21725b8b

Per https://github.com/alsa-project/alsa-ucm-conf/pull/134 , ALSA UCM support for PinePhone is now in upstream, so this can and should be removed from this repo.

This will fix:

• the PR issue: #3
• a bug whose fix is in upstream: #1