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>

pkgs/misc/riscv-pk/default.nix

@@ -0,0 +1,41 @@
+{ lib, stdenv, fetchFromGitHub, autoreconfHook, payload ? null }:
+
+stdenv.mkDerivation rec {
+  pname = "riscv-pk";
+  version = "1.0.0";
+
+  src = fetchFromGitHub {
+    owner = "riscv";
+    repo = "riscv-pk";
+    rev = "v${version}";
+    sha256 = "1cc0rz4q3a1zw8756b8yysw8lb5g4xbjajh5lvqbjix41hbdx6xz";
+  };
+
+  nativeBuildInputs = [ autoreconfHook ];
+
+  preConfigure = ''
+    mkdir build
+    cd build
+  '';
+
+  configureScript = "../configure";
+
+  configureFlags = lib.optional (payload != null)
+    "--with-payload=${payload}";
+
+  hardeningDisable = [ "all" ];
+
+  postInstall = ''
+    mv $out/* $out/.cleanup
+    mv $out/.cleanup/* $out
+    rmdir $out/.cleanup
+  '';
+
+  meta = {
+    description = "RISC-V Proxy Kernel and Bootloader";
+    homepage = "https://github.com/riscv/riscv-pk";
+    license = lib.licenses.bsd3;
+    platforms = lib.platforms.riscv;
+    maintainers = [ lib.maintainers.shlevy ];
+  };
+}