Cleanup the last pixel3_mainline reference am: 4714ee4dc0 am: 222eb0c053 am: a883eb0dfa

Original change: https://android-review.googlesource.com/c/device/linaro/dragonboard/+/2004160

Change-Id: I16bf37ddebccf8764bf8f18dc68ee7ad22f65896
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>