uboot: (firmwareOdroidC2/C4) don't invoke patch tool, use patches = [] instead

https://github.com/NixOS/nixpkgs/blob/master/pkgs/stdenv/generic/setup.sh#L948
this can do it nicely.

Signed-off-by: Anton Arapov <anton@deadbeef.mx>

nixos/modules/services/network-filesystems/cachefilesd.nix

@@ -0,0 +1,63 @@
+{ config, pkgs, lib, ... }:
+
+with lib;
+
+let
+
+  cfg = config.services.cachefilesd;
+
+  cfgFile = pkgs.writeText "cachefilesd.conf" ''
+    dir ${cfg.cacheDir}
+    ${cfg.extraConfig}
+  '';
+
+in
+
+{
+  options = {
+    services.cachefilesd = {
+
+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = "Whether to enable cachefilesd network filesystems caching daemon.";
+      };
+
+      cacheDir = mkOption {
+        type = types.str;
+        default = "/var/cache/fscache";
+        description = "Directory to contain filesystem cache.";
+      };
+
+      extraConfig = mkOption {
+        type = types.lines;
+        default = "";
+        example = "brun 10%";
+        description = "Additional configuration file entries. See cachefilesd.conf(5) for more information.";
+      };
+
+    };
+  };
+
+  ###### implementation
+
+  config = mkIf cfg.enable {
+
+    boot.kernelModules = [ "cachefiles" ];
+
+    systemd.services.cachefilesd = {
+      description = "Local network file caching management daemon";
+      wantedBy = [ "multi-user.target" ];
+      serviceConfig = {
+        Type = "exec";
+        ExecStart = "${pkgs.cachefilesd}/bin/cachefilesd -n -f ${cfgFile}";
+        Restart = "on-failure";
+        PrivateTmp = true;
+      };
+    };
+
+    systemd.tmpfiles.rules = [
+      "d ${cfg.cacheDir} 0700 root root - -"
+    ];
+  };
+}