OTA: update SetBlockDeviceReadOnly am: fc20b67da1

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2745153

Change-Id: I28fc57795c59343cd626cfb5a189cce134569124
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>