vc4-hdmi.conf: use a proper hdmi pcm, fix broken default pcm

[GitHub issues - opened]

alsa-project/alsa-lib issue #229 was opened from macmpi:

referring https://github.com/raspberrypi/linux/issues/4662#issuecomment-1114000673 and assorted [patch](https://mailman.alsa-project.org/pipermail/alsa-devel/2022-April/200025.html) from @HiassofT
Thanks for consideration.

Issue URL     : https://github.com/alsa-project/alsa-lib/issues/229
Repository URL: https://github.com/alsa-project/alsa-lib