msm: mdss: idle power collapse notify

This fix adds notification of idle power collapse to user space
for cmd mode panels. Without this fix user space has no
knowledge of reprogramming the QSEED3 LUTs after idle power
collapse, this needs to be done with the user space knowledge
to keep it's LUT bank offset in sync with the HW used LUT bank
offset.

Change-Id: Ia1fbd07da8c8c854a74cf5dad62f5ec2d1fc962e
Signed-off-by: Abhijit Kulkarni <kabhijit@codeaurora.org>