Grab lock before reparenting in SurfaceFlinger commitMirrorDisplays()

Bug: 271644537
Test: n/a
Change-Id: I45384210791bd9280f63d95e3bdaef3d299fc818
(cherry picked from commit 9cba62a07f393d852dabf20b6e4d10e67b29c8d9)
Merged-In: I45384210791bd9280f63d95e3bdaef3d299fc818
1 file changed