MLK-22653-1 drm/imx: dpu: crtc: Send vblank event after drm_crtc_vblank_off() in...

MLK-22653-1 drm/imx: dpu: crtc: Send vblank event after drm_crtc_vblank_off() in ->atomic_disable()

The Kdoc for the event entry of struct drm_crtc_state mentions that the
simplest way to send vblank event when a CRTC is being disabled is that
calling drm_crtc_send_vblank_event() somewhen after drm_crtc_vblank_off()
has been called.  This patch takes the way mentioned above to send vblank
event in the ->atomic_disable() callback.

Signed-off-by: Liu Ying <victor.liu@nxp.com>
(cherry picked from commit 5b1a8127d98daf13d9f9891dfad2589f339b63d5)