hosts: nixos: porthos: migrate to new host

OVH/Kimsufi are deprecating my current server by the end of the year. So
let's migrate to a new host.

This was more painful than initially planned, OVH introduced a change to
their rescue system which messes with the NixOS installation [1].

In the end I used a kexec image [2] to run the installation.

[1]: https://github.com/NixOS/nix/issues/7790
[2]: https://github.com/nix-community/nixos-images

hosts/nixos/porthos/hardware.nix

@@ -1,5 +1,5 @@
 # Hardware configuration
-{ lib, modulesPath, ... }:
+{ modulesPath, ... }:
 
 {
   imports = [
@@ -11,9 +11,18 @@
     fsType = "ext4";
   };
 
+  fileSystems."/boot" = {
+    device = "/dev/disk/by-label/boot";
+    fsType = "vfat";
+  };
+
   swapDevices = [
     { device = "/dev/disk/by-label/swap"; }
   ];
 
-  powerManagement.cpuFreqGovernor = lib.mkDefault "ondemand";
+  my.hardware = {
+    firmware = {
+      cpuFlavor = "intel";
+    };
+  };
 }