common/pc/laptop: drop explicit vm.laptop_mode

This is handled by TLP, so we don't need to set that explicitly.

common/pc/laptop/default.nix

@@ -1,16 +1,13 @@
-{ lib, ... }:
+{ config, lib, ... }:
 
 {
   imports = [ ../. ];
 
-  boot.kernel.sysctl = {
-    "vm.laptop_mode" = lib.mkDefault 5;
-  };
-
   # TODO: fix in NixOS/nixpkgs
   # Disable governor set in hardware-configuration.nix,
   # required when services.tlp.enable is true:
-  powerManagement.cpuFreqGovernor = lib.mkForce null;
+  powerManagement.cpuFreqGovernor =
+    lib.mkIf config.services.tlp.enable (lib.mkForce null);
 
   services.tlp.enable = lib.mkDefault true;
 }