disp: msm: sde: wait for specific pp_done instead of zero

2 Frames transfer pending is possible with posted start.
One ongoing frame and another triggered frame. Current SW
waits for pp_done interrupt if pending frame count is greater
than 1. It is possible that interrupt may be missed for ongoing
frame. In that case, SW should run pp_done wait for one by one
frame instead of two frames together. It allows encoder to
check the ctl scheduler status and trigger the frame done
event on time.

Change-Id: I4817842292d96747890ee70da8a5bdf9b56816ed
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>
Signed-off-by: Ray Zhang <rayz@codeaurora.org>
Signed-off-by: Bruce Hoo <bingchua@codeaurora.org>