Using the walk_device_tree helper, we can walk the device tree from the
beginning looking for a specific property node. It's still missing the
ability to get property lists, string lists, and property-specific data.
We have a new, improved string type coming up in AK (OOM aware, no null
state), and while it's going to use UTF-8, the name UTF8String is a
mouthful - so let's free up the String name by renaming the existing
class.
Making the old one have an annoying name will hopefully also help with
quick adoption :^)
