disp: msm: sde: avoid zero BW votes in cases where planes are staged

During low power state transitions, populate MNOC AB, MNOC per_pipe_ib
and core_clk values from the old state in cases where current state
values are zeros from userspace but planes are staged.

Change-Id: Iaafdbc9be78d4cfb12ee9cefdcf96030c05f5c6d
Signed-off-by: Jayaprakash <jmadiset@codeaurora.org>