drm/i915: use VLV DIP routines on VLV v2

This fixes up broken logic introduced in

commit 90b107c8
Author: Shobhit Kumar <shobhit.kumar@intel.com>
Date:   Wed Mar 28 13:39:32 2012 -0700

    drm/i915: Enable HDMI on ValleyView

That one was probably a rebase fail along the way.

v2: clean up init ordering (Daniel)

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
[danvet: Pimp commit message a bit.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>