feat(3p/kernelPatches): Add kernel audio patch for ASUS TRX40 Pro

Without this patch, this board is not included in the pin map
overrides and audio basically doesn't work.

With this patch, the audio still doesn't work, but it can at least
correctly detect what is and isn't plugged in - so that's progress.

Change-Id: I66ca7d7a1e0e25a0212b9659381875ad4c590ffc
Reviewed-on: https://cl.tvl.fyi/c/depot/+/542
Reviewed-by: lukegb <lukegb@tvl.fyi>

third_party/kernelPatches/trx40_usb_audio/default.nix

@@ -0,0 +1,9 @@
+# This patch adds the ASUS TRX40 Prime Pro Whatever Edition
+# motherboard to the list of boards for which the USB Audio connector
+# map has been fixed.
+{ ... }:
+
+{
+  name = "trx40_usb_audio";
+  patch = ./trx40_usb_audio.patch;
+}