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/os-specific/linux/kernel/linux-testing.nix

@@ -0,0 +1,20 @@
+{ lib, buildPackages, fetchurl, perl, buildLinux, nixosTests, modDirVersionArg ? null, ... } @ args:
+
+with lib;
+
+buildLinux (args // rec {
+  version = "5.15-rc6";
+  extraMeta.branch = lib.versions.majorMinor version;
+
+  # modDirVersion needs to be x.y.z, will always add .0
+  modDirVersion = if (modDirVersionArg == null) then builtins.replaceStrings ["-"] [".0-"] version else modDirVersionArg;
+
+  src = fetchurl {
+    url = "https://git.kernel.org/torvalds/t/linux-${version}.tar.gz";
+    sha256 = "1lp3jqwsbd97k3bx4crs8rc2wssyaf0v8x4kl4zv7g7ww2kkg2ii";
+  };
+
+  # Should the testing kernels ever be built on Hydra?
+  extraMeta.hydraPlatforms = [];
+
+} // (args.argsOverride or {}))