xanmod-kernels: remove explicit WERROR=n

pkgs/os-specific/linux/kernel/xanmod-kernels.nix

@@ -24,13 +24,7 @@ let
       inherit hash;
     };
 
-    structuredExtraConfig =
-      with lib.kernel;
-      with (lib.kernel.whenHelpers version);
-      {
-        # TODO: remove this once https://github.com/NixOS/nixpkgs/pull/175433 is in master
-        WERROR = no;
-
+    structuredExtraConfig = with lib.kernel; {
       # removed options
       CFS_BANDWIDTH = lib.mkForce (option no);
       RT_GROUP_SCHED = lib.mkForce (option no);