drm/msm/disp/dpu: wait for extra vsync till timing engine status is disabled

There can be a race between timing gen disable and vblank irq. The
wait post timing gen disable may return early but intf disable sequence
might not be completed. Ensure that, intf status is disabled before
we retire the function.

Signed-off-by: Vinod Polimera <quic_vpolimer@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/524727/
Link: https://lore.kernel.org/r/1677774797-31063-7-git-send-email-quic_vpolimer@quicinc.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>