ALSA: hda/hdmi: Static PCM mapping again with AMD HDMI codecs

The recent code refactoring for HD-audio HDMI codec driver caused a
regression on AMD/ATI HDMI codecs; namely, PulseAudioand pipewire
don't recognize HDMI outputs any longer while the direct output via
ALSA raw access still works.

The problem turned out that, after the code refactoring, the driver
assumes only the dynamic PCM assignment, and when a PCM stream that
still isn't assigned to any pin gets opened, the driver tries to
assign any free converter to the PCM stream.  This behavior is OK for
Intel and other codecs, as they have arbitrary connections between
pins and converters.  OTOH, on AMD chips that have a 1:1 mapping
between pins and converters, this may end up with blocking the open of
the next PCM stream for the pin that is tied with the formerly taken
converter.

Also, with the code refactoring, more PCM streams are exposed than
necessary as we assume all converters can be used, while this isn't
true for AMD case.  This may change ...