Use android::binder::unique_fd am: 057367ffbb

Original change: https://android-review.googlesource.com/c/trusty/app/sample/+/2853573

Change-Id: Id545412ea19170730d7288d8ff64eaafad7baab3
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>