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/tools/misc/xilinx-bootgen/default.nix

@@ -0,0 +1,37 @@
+{ lib, stdenv, fetchFromGitHub, openssl }:
+
+stdenv.mkDerivation {
+  pname = "xilinx-bootgen";
+  version = "unstable-2019-10-23";
+
+  src = fetchFromGitHub {
+    owner = "xilinx";
+    repo = "bootgen";
+    rev = "f9f477adf243fa40bc8c7316a7aac37a0efd426d";
+    sha256 = "1qciz3jkzy0z0lcgqnhch9pqj0202mk5ghzp2m9as5pzk8n8hrbz";
+  };
+
+  buildInputs = [ openssl ];
+
+  enableParallelBuilding = true;
+
+  installPhase = ''
+    install -Dm755 bootgen $out/bin/bootgen
+  '';
+
+  meta = with lib; {
+    description = "Generate Boot Images for Xilinx Zynq and ZU+ SoCs";
+    longDescription = ''
+      Bootgen for Xilinx Zynq and ZU+ SoCs, without code related to generating
+      obfuscated key and without code to support FPGA encryption and
+      authentication. These features are only available as part of Bootgen
+      shipped with Vivado tools.
+
+      For more details about Bootgen, please refer to Xilinx UG1283.
+    '';
+    homepage = "https://github.com/Xilinx/bootgen";
+    license = licenses.asl20;
+    platforms = platforms.linux;
+    maintainers = [ maintainers.flokli ];
+  };
+}