disp: msm: sde: schedule idle notify after frame trigger

Existing idle notify schedule logic tries to schedule
this event before display power on. If display power on
takes more than 80ms, it triggers the idle notify before
processing first display power on frame. This patch
schedules the idle notify after frame trigger for
valid notification.

Change-Id: If94108e141b5c19d123033e9d37333e98fb987f7
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>