Fix how displays are used in test cases am: 017cb98e

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/2305821



Change-Id: I95e906a94413fe0d896573fb66d27c84a9befb66
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>