libhwc2.1: OperationRateManager: save target operation rate am: abd1d92d70

Original change: https://googleplex-android-review.googlesource.com/c/platform/hardware/google/graphics/zuma/+/23844793

Change-Id: Id3c4602aa249a59a92cc2b10f7b5c7061e276f0a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>