Give TLP more control over the battery and enable battery life saver parameters

lenovo/thinkpad/x1/6th-gen/QHD/default.nix

@@ -1,9 +1,26 @@
 # X1 6th generation with a QHD (2560x1440px) display
+{ config,  ... }:
+
 {
   imports = [
     ../.
   ];
+  # give tlp more control over battery
+  boot = {
+    extraModulePackages = with config.boot.kernelPackages; [
+      acpi_call
+    ];
+    kernelModules = [
+      "acpi_call"
+    ];
+  };
 
+  # see https://linrunner.de/en/tlp/docs/tlp-faq.html#battery
+  services.tlp.extraConfig = ''
+START_CHARGE_THRESH_BAT0=75
+STOP_CHARGE_THRESH_BAT0=80
+'';
+  # fix font sizes in X
   services.xserver.dpi = 210;
   fonts.fontconfig.dpi = 210;
 }