Update 'hosts/nixos/hardware.nix'

Signed-off-by: Christopher James Hayward <chris@chrishayward.xyz>

hosts/nixos/hardware.nix

@@ -16,7 +16,7 @@
   boot.loader.grub.device = "/dev/sda";
 
   fileSystems."/" =
-    { # device = "/dev/disk/by-label/nixos";
+    { device = "/dev/disk/by-label/nixos";
       fsType = "ext4";
     };