disp: msm: sde: add cached lut flag in sde plane

Below is the sequence during which issue is observed
while using stale lut values:

1) Scaler block is enabled in the VIG pipe along with the
valid lut configuration.

2) Idle work gets scheduled and GDSC is turned off erasing
the saved lut values.

3) At the same time, userspace sends a commit assuming lut
values are still valid resulting in artifacts on the
screen.

In the plane state scaler config, only lut flag will be
reset for subsequent commits and remaining properties such
as filter cfgs, lut_idx etc. remains same. This change
caches the lut flag in sde plane whenever the lut is being
set and reuses this flag to handle above issue.

Change-Id: Ia6a2f3fb3fe2368f8accb4453082d11d7d75756b
Signed-off-by: Yashwanth <yvulapu@codeaurora.org>