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/installer/sd-card/sd-image-x86_64.nix

@@ -0,0 +1,27 @@
+# To build, use:
+# nix-build nixos -I nixos-config=nixos/modules/installer/sd-card/sd-image-x86_64.nix -A config.system.build.sdImage
+
+# This image is primarily used in NixOS tests (boot.nix) to test `boot.loader.generic-extlinux-compatible`.
+{ config, lib, pkgs, ... }:
+
+{
+  imports = [
+    ../../profiles/base.nix
+    ./sd-image.nix
+  ];
+
+  boot.loader = {
+    grub.enable = false;
+    generic-extlinux-compatible.enable = true;
+  };
+
+  boot.consoleLogLevel = lib.mkDefault 7;
+
+  sdImage = {
+    populateFirmwareCommands = "";
+    populateRootCommands = ''
+      mkdir -p ./files/boot
+      ${config.boot.loader.generic-extlinux-compatible.populateCmd} -c ${config.system.build.toplevel} -d ./files/boot
+    '';
+  };
+}