Use the new drm_gem_framebuffer_helper who's code was copied
from this helper.
Signed-off-by: NNoralf Trønnes <noralf@tronnes.org>
Reviewed-by: NEric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/1502631125-13557-3-git-send-email-noralf@tronnes.org