Load acpi_call module only if tlp is being used

power-profiles-daemon cannot use acpi_call. This avoids taining
the kernel by installing an unnecessary kernel module.

common/pc/laptop/acpi_call.nix

@@ -1,9 +1,9 @@
 # acpi_call makes tlp work for newer thinkpads
 
-{ config, ... }:
+{ config, lib, ... }:
 
 {
-  boot = {
+  boot = lib.mkIf config.services.tlp.enable {
     kernelModules = [ "acpi_call" ];
     extraModulePackages = with config.boot.kernelPackages; [ acpi_call ];
   };