drm: vc4: use vblank hooks in struct drm_crtc_funcs

The vblank hooks in struct drm_driver are deprecated and only meant for
legacy drivers.  For modern drivers with DRIVER_MODESET flag, the hooks
in struct drm_crtc_funcs should be used instead.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Cc: Eric Anholt <eric@anholt.net>
Reviewed-by: Eric Anholt <eric@anholt.net>
Link: http://patchwork.freedesktop.org/patch/msgid/1486458995-31018-23-git-send-email-shawnguo@kernel.org

drivers/gpu/drm/vc4/vc4_drv.c

@@ -137,8 +137,6 @@ static struct drm_driver vc4_drm_driver = {
 	.irq_postinstall = vc4_irq_postinstall,
 	.irq_uninstall = vc4_irq_uninstall,
 
-	.enable_vblank = vc4_enable_vblank,
-	.disable_vblank = vc4_disable_vblank,
 	.get_scanout_position = vc4_crtc_get_scanoutpos,
 	.get_vblank_timestamp = vc4_crtc_get_vblank_timestamp,