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/rxe.nix

@@ -0,0 +1,52 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.networking.rxe;
+
+in {
+  ###### interface
+
+  options = {
+    networking.rxe = {
+      enable = mkEnableOption "RDMA over converged ethernet";
+      interfaces = mkOption {
+        type = types.listOf types.str;
+        default = [ ];
+        example = [ "eth0" ];
+        description = ''
+          Enable RDMA on the listed interfaces. The corresponding virtual
+          RDMA interfaces will be named rxe_<interface>.
+          UDP port 4791 must be open on the respective ethernet interfaces.
+        '';
+      };
+    };
+  };
+
+  ###### implementation
+
+  config = mkIf cfg.enable {
+
+    systemd.services.rxe = {
+      description = "RoCE interfaces";
+
+      wantedBy = [ "multi-user.target" ];
+      after = [ "systemd-modules-load.service" "network-online.target" ];
+      wants = [ "network-pre.target" ];
+
+      serviceConfig = {
+        Type = "oneshot";
+        RemainAfterExit = true;
+        ExecStart = map ( x:
+          "${pkgs.iproute2}/bin/rdma link add rxe_${x} type rxe netdev ${x}"
+          ) cfg.interfaces;
+
+        ExecStop = map ( x:
+          "${pkgs.iproute2}/bin/rdma link delete rxe_${x}"
+          ) cfg.interfaces;
+      };
+    };
+  };
+}
+