Bug#905969: amdgpu: only one audio port shows up in pulseaudio

[Alexis Hunt <alercah@gmail.com>]

Source: linux
Severity: normal

Dear Maintainer,

I have a Radeon RX580 card with two DisplayPort ports, in a dual-head monitor
setup. When I look at the corresponding audio sink with pulseaudio, however, I
find that there is only one output port listed, and so I cannot select which
port I wish to send audio out on.

Both ports work for audio; if the current-active monitor is disconnected, then
the audio will automatically switch to the other one. It is just that they are
not both exposed simultaneously to pulseaudio as being selectable.

-- System Information:
Debian Release: buster/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 4.17.0-1-amd64 (SMP w/16 CPU cores)
Locale: LANG=en_CA.UTF-8, LC_CTYPE=en_CA.UTF-8 (charmap=UTF-8), LANGUAGE=en_CA:en (charmap=UTF-8)
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)