Instead of going through a complicated private IRQ registration
mechanism, handle the vblank interrupt activation with the standard
drm_crtc_vblank_get() and drm_crtc_vblank_put() mechanism. This will let
the DRM core keep the vblank interrupt enabled as long as needed to
update the frame counter.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>