use openwrt kernel for gl-ar750

kernel/default.nix

@@ -1,44 +1,19 @@
 {
   callPackage
-, buildPackages
-, stdenvNoCC
-, fetchFromGitHub
 
 , config
 , checkedConfig
 , sources
 }:
-let
-  # The kernel is huge and takes a long time just to
-  # download and unpack. This derivation creates
-  # a source tree in a suitable shape to build from -
-  # today it just patches some scripts but as we add
-  # support for boards/SoCs we expect the scope of
-  # "pre-treatment" to grow
-
-  tree = stdenvNoCC.mkDerivation {
-    name = "spindled-kernel-tree";
-    src = sources.kernel;
-    phases = [ "unpackPhase" "patchPhase" "patchScripts" "installPhase" ];
-    patches = [ ./random.patch ];
-    patchScripts = ''
-      patchShebangs scripts/
-    '';
-    installPhase = ''
-      mkdir -p $out
-      cp -a . $out
-    '';
-  };
-
-in rec {
+{
   vmlinux = callPackage ./vmlinux.nix {
-    inherit tree config checkedConfig;
+    tree = sources.kernel;
+    inherit config checkedConfig;
   };
 
   uimage = callPackage ./uimage.nix { };
 
   dtb = callPackage ./dtb.nix {
-    openwrt = sources.openwrt;
-    kernel = tree;
+    inherit (sources) openwrt kernel;
   };
 }

kernel/vmlinux.nix

@@ -92,8 +92,9 @@ stdenv.mkDerivation rec {
   installPhase = ''
     ${CROSS_COMPILE}strip -d vmlinux
     cp vmlinux $out
-    make clean
     mkdir -p $modulesupport
+    cp .config $modulesupport/config
+    make clean
     cp -a . $modulesupport
   '';