lib: Add DTB extraction lib from boot_params structure am: 9d11ecae22

Original change: https://android-review.googlesource.com/c/trusty/lk/trusty/+/3322954

Change-Id: I175c3bbfaadc3fe5c452802032647488106ddf8e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>