disp: msm: sde: avoid idle notify cancel request

SDE crtc module can trigger idle notify for video
mode display by updating existing scheduled work
instead of cancelling and rescheduling it.

Change-Id: I1c4b93a3701bbebe0487c4a0da35aff586315398
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>