Add bufferpool AIDL definitions am: 1468ddfbf3

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/2283539

Change-Id: I8e633fdf31c913335fc0df292ffac7afb65c8e0e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>