Reorganize imports

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

hosts/common/configs/system/cpu/default.nix

@@ -0,0 +1,4 @@
+{ ... }:
+{
+  imports = [ ./options.nix ];
+}

hosts/common/configs/system/cpu/options.nix

@@ -0,0 +1,17 @@
+{ lib, ... }:
+{
+  options.hardware.cpu =
+    with lib;
+    with types;
+    {
+      cores = mkOption {
+        type = ints.positive;
+        description = "The number of cpu cores.";
+      };
+
+      threads = mkOption {
+        type = ints.positive;
+        description = "The number of cpu threads.";
+      };
+    };
+}