Segregate lenovo/ subdir into thinkpad and ideapad directories

There are several significant differences between ThinkPads and the
other Lenovo models, so this structure must be more precise

lenovo/thinkpad/t440p.nix

@@ -0,0 +1,12 @@
+{ config, pkgs, ... }:
+
+{
+  imports = [ ./general.nix ];
+
+  boot = {
+    extraModprobeConfig = ''
+      options bbswitch use_acpi_to_detect_card_state=1
+    '';
+    kernelModules = [ "kvm-intel" "tpm-rng" ];
+  };
+}