Cleanup the last pixel3_mainline reference am: 4714ee4dc0

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

Change-Id: If62446c57a8a55b8384a4fdf7f1a14bc663e82f4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>