disp: msm: sde: remove fb's attached to a drm_file in preclose

Add changes to remove framebuffers attached to a drm_file
in preclose whose refcount is not managed by composer kill
and issue null flush to hardware in such cases. This will
avoid upstream issuing drm_atomic_commit's in drm_fb_release
which is leading to artifacts on screen or atomic_check failures
due to atomically unstaging each fb from plane_state and
committing remaining planes on hardware.

Change-Id: Ic197fb596a1dcfd1ebe2c83e759e619a1ab2f798
Signed-off-by: Jayaprakash <jmadiset@codeaurora.org>