pvmfw: apply_debug_policy: Backup DT before unpacking am: 1c9b08f146

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/modules/Virtualization/+/23107373

Change-Id: Idff2686be2a7a7d69df6ed1a0400cf7f203650fb
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>