amdadl-sdk: set license to unfree (close #1647)

We cannot auto build amdadl-sdk on hydra, so setting license to unfree disable
auto builds. I also remove amdadl license, because it's irrelevant.

vcunat changed string license to attribute.

pkgs/development/misc/amdadl-sdk/default.nix

@@ -42,7 +42,7 @@ stdenv.mkDerivation rec {
   meta = with stdenv.lib; {
     description = "API to access display driver functionality for ATI graphics cards";
     homepage = http://developer.amd.com/tools/graphics-development/display-library-adl-sdk/;
-    license = licenses.amdadl;
+    license = "unfree";
     maintainers = [ maintainers.offline ];
     platforms = stdenv.lib.platforms.linux;
     hydraPlatforms = [];