chipsec: restrict to x86-only

package is unlikely to support other platforms in the near
future - see https://github.com/chipsec/chipsec/issues/461

pkgs/tools/security/chipsec/default.nix

@@ -68,6 +68,6 @@ python3.pkgs.buildPythonApplication rec {
     license = licenses.gpl2Only;
     homepage = "https://github.com/chipsec/chipsec";
     maintainers = with maintainers; [ johnazoidberg ];
-    platforms = if withDriver then [ "x86_64-linux" ] else platforms.all;
+    platforms = [ "x86_64-linux" ] ++ lib.optional (!withDriver) "x86_64-darwin";
   };
 }