dtc: Audit and fix valgrind errors

[Jon Loeliger]

> The somewhat embarrasing bug in the first version of my previous patch
> would have been detected by valgrind.  Thus reminded, I've run the
> testsuite under valgrind and fixed any errors I found.  This turned
> out to be just some uninitialized buffers in test programs.  The
> fragments of uninitialized data aren't particularly important, but we
> might as well squash the valgrind warnings, so that future valgrind
> errors will stand out.
> 
> Signed-off-by: David Gibson <david at gibson.dropbear.id.au>

Applied.

Thanks,
jdl