Preparations for system as root

This mostly involves moving the DTB files plus some cleanups in
the Android.mk

Partial cherry-pick of Ibd011c6f2a7cdfdc36e695e717b337b563784876

Bug: 110097226
Change-Id: I6e6bc89fc20e430bdfbe376a0272d225577bf79c
Test: Local build and boot
(cherry picked from commit 68d5f9872043ec71a4526c41fa9d84ce723af76e)
4 files changed