Correct the map size before accessing in VTS test am: 72b8a3a7ce

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/3411437

Change-Id: I4f566b136aa43ac8a07afbcc80d3742771aaf1cb
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>