Disallow fastboot to modify locked DSU am: bcbc93f83d

Original change: https://googleplex-android-review.googlesource.com/c/platform/system/core/+/24687344

Change-Id: I39e87e4ccbb8af91c729d105bc3de59f4be61cd0
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>