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

This change avoids upstream drm issuing drm_atomic_commit 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.

 a) This patch moves the state operations for setting crtc to
    connector state to a helper api.
 b) This patch clears any dim_layers present in the crtc_state
    as part of null commit.
 c) This patch removes any framebuffers attached to a drm_file
    in msm_preclose whose refcount is not managed by composer kill
    inadvertently and issues null flush to hardware in such cases.
 d) This patch handles msm_preclose as part of msm_release
    operation since legacy feature is not supported
    for msm_driver.

Change-Id: Ib2068d74d4b23b73b7c84544858c9f6bb6adfa67
Signed-off-by: Jayaprakash Madisetty <jmadiset@codeaurora.org>