SF: Fix deadlock during display hotplug

I30ec756f134d2d67a70ac8797008dc792eac035e laid the foundation to remove
the offending lock, but declared victory prematurely.

Fixes: 329450361
Flag: EXEMPT bugfix
Test: presubmit
Change-Id: Iaae02d95e175e55f52f65da1481b64f1f533a04c
2 files changed