drm/hdlcd: remove drm_vblank_cleanup, rise of the zoombies edition

This was accidentally restored in

commit de5cc815
Author: Liviu Dudau <Liviu.Dudau@arm.com>
Date:   Tue Jun 6 15:05:21 2017 +0100

    drm/arm: hdlcd: Set the CRTC's port before binding the encoder

Fixes: de5cc815 ("drm/arm: hdlcd: Set the CRTC's port before binding the encoder.")
Cc: Liviu Dudau <Liviu.Dudau@arm.com>
Cc: Brian Starkey <brian.starkey@arm.com>
Cc: Mali DP Maintainers <malidp@foss.arm.com>
Acked-by: Liviu Dudau <Liviu.Dudau@arm.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170628091141.14539-1-daniel.vetter@ffwll.ch