drm/msm/sde: trigger retire fence early for qsync frame

CTL_START irq is triggered after rd_ptr irq and beyond
500us threshold for QSYNC enabled usecase. This CTL_START
irq should trigger the retire fence instead of PP_DONE
irq. It releases gpu buffer early and helps to achieve
higher FPS for double buffer usecase.

Change-Id: Idb1e1458b08d9148b2d412094e2ba044209e7a78
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>