[U-Boot] Please update libfdt for U-Boot

Jerry,

Now that the merge window is open, could you please update libfdt? The version in U-Boot hasn't been updated in over a year, and there are new features that I need to have. Specifically, this commit: http://git.jdl.com/gitweb/?p=dtc.git;a=commit;h=d75b33af676d0beac8398651a7f0...