move filesystems to modules

modules/sys/fs/mounts/efi.nix

@@ -0,0 +1,7 @@
+{
+  fileSystems."/boot" =
+    { device = "/dev/disk/by-label/EFI";
+      fsType = "vfat";
+      options = [ "fmask=0077" "dmask=0077" ];
+    };
+}

modules/sys/fs/mounts/root-btrfs.nix

@@ -0,0 +1,7 @@
+{
+  fileSystems."/" =
+    { device = "/dev/disk/by-label/NixOS";
+      fsType = "btrfs";
+      options = [ "discard" ];
+    };
+}

modules/sys/fs/mounts/swap.nix

@@ -0,0 +1,5 @@
+{
+  swapDevices = [{ device = "/dev/disk/by-label/Swap";
+    options = [ "discard" "nofail" ];
+  }];
+}