wireplumber: Disable C920 webcam microphone

On the desktop, we use the USB microphone and the C920 being selected
as the default was becoming annoying. Add a rule to disable C920 node
acting as an audio microphone input. The video source provided by C920
will still be functional. We are only turning off the Audio/Source
node and not the complete device.

wireplumber/.config/wireplumber/main.lua.d/51-alsa-disable.lua

@@ -0,0 +1,10 @@
+disable_C920_mic_rule = {
+  matches = {
+    {
+      { "node.nick", "equals", "HD Pro Webcam C920" },
+      { "media.class", "equals", "Audio/Source" },
+    },
+  },
+  apply_properties = { ["node.disabled"] = true, },
+}
+table.insert(alsa_monitor.rules, disable_C920_mic_rule)