Refactor device tree

It's quite a mess right now - this commit makes it a lot cleaner.

Change-Id: I0fe2d9994afe44207b267e60e237c9c997aa6e72
Merge commit 'refs/changes/01/68201/1' of ssh://review.cyanogenmod.org:29418/CyanogenMod/android_device_samsung_tuna into exp