DEVELOPERS: Add some more entries for Thomas Huth

I'm involved in the upstream kvm-unit-tests and the mcf5208 QEMU
machine, so I could help to have a look on these files, too.

Signed-off-by: Thomas Huth <huth@tuxfamily.org>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>