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/networking/radvd.nix

@@ -0,0 +1,77 @@
+# Module for the IPv6 Router Advertisement Daemon.
+
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+
+  cfg = config.services.radvd;
+
+  confFile = pkgs.writeText "radvd.conf" cfg.config;
+
+in
+
+{
+
+  ###### interface
+
+  options = {
+
+    services.radvd.enable = mkOption {
+      type = types.bool;
+      default = false;
+      description =
+        ''
+          Whether to enable the Router Advertisement Daemon
+          (<command>radvd</command>), which provides link-local
+          advertisements of IPv6 router addresses and prefixes using
+          the Neighbor Discovery Protocol (NDP).  This enables
+          stateless address autoconfiguration in IPv6 clients on the
+          network.
+        '';
+    };
+
+    services.radvd.config = mkOption {
+      type = types.lines;
+      example =
+        ''
+          interface eth0 {
+            AdvSendAdvert on;
+            prefix 2001:db8:1234:5678::/64 { };
+          };
+        '';
+      description =
+        ''
+          The contents of the radvd configuration file.
+        '';
+    };
+
+  };
+
+
+  ###### implementation
+
+  config = mkIf cfg.enable {
+
+    users.users.radvd =
+      {
+        isSystemUser = true;
+        group = "radvd";
+        description = "Router Advertisement Daemon User";
+      };
+    users.groups.radvd = {};
+
+    systemd.services.radvd =
+      { description = "IPv6 Router Advertisement Daemon";
+        wantedBy = [ "multi-user.target" ];
+        after = [ "network.target" ];
+        serviceConfig =
+          { ExecStart = "@${pkgs.radvd}/bin/radvd radvd -n -u radvd -C ${confFile}";
+            Restart = "always";
+          };
+      };
+
+  };
+
+}