Read Verified Boot key from system property in default KeyMint implementation. am: c1bf5f8a6d am: bebc8974ab

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/3360186

Change-Id: I368a735e7ea710d04f0333845bd82be2bbbfea93
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>