framework: Fix TRRS headphones missing a mic

As in the below forum post, this is not perhaps the most ideal solution
to the problem, but it is the simplest.

https://community.frame.work/t/headset-microphone-on-linux/12387/3

framework/default.nix

@@ -13,6 +13,12 @@
   # https://community.frame.work/t/using-the-ax210-with-linux-on-the-framework-laptop/1844/89
   boot.kernelPackages = lib.mkIf (lib.versionOlder pkgs.linux.version "5.16") (lib.mkDefault pkgs.linuxPackages_latest);
 
+  # Fix TRRS headphones missing a mic
+  # https://community.frame.work/t/headset-microphone-on-linux/12387/3
+  boot.extraModprobeConfig = ''
+    options snd-hda-intel model=dell-headset-multi
+  '';
+
   # For fingerprint support
   services.fprintd.enable = true;