SurfaceFlinger: Dont skip composition if it is incomplete.

If the composition is not complete because of suspend we need at least
one complete composition to happen without skipping.

Set force composition flag so that next time hwc does not skip the
composition.

CRs-fixed: 374830
(cherry picked from commit f03f679fc34eb839c801330e58c3c898a392a3b6)

Change-Id: Id907e6ff259aef7caec32c6edc44bb6082c583bb