cbfstool: 4.5 -> 4.7, fixes build

pkgs/applications/virtualization/cbfstool/default.nix

···
 
 stdenv.mkDerivation rec {
   name = "cbfstool-${version}";
-  version = "4.5";
+  version = "4.7";
 
   src = fetchgit {
     url = "http://review.coreboot.org/p/coreboot";
     rev = "refs/tags/${version}";
-    sha256 = "0sc2h440x4sfp1lqnmh3xfgymf7j0rqfx00v6jqf0svfbp8a6cq5";
+    sha256 = "02k63013vf7wgsilslj68fs1x81clvqpn91dydaqhv5aymh73zpi";
   };
 
   nativeBuildInputs = [ flex bison ];