Revert "drm/i915: don't touch the VDD when disabling the panel"

This reverts
commit dff392db
Author: Paulo Zanoni <paulo.r.zanoni@intel.com>
Date:   Fri Dec 6 17:32:41 2013 -0200

    drm/i915: don't touch the VDD when disabling the panel

which didn't take into account

commit 6cb49835
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Sun May 20 17:14:50 2012 +0200

    drm/i915: enable vdd when switching off the eDP panel

and

commit 35a38556


Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Sun Aug 12 22:17:14 2012 +0200

    drm/i915: reorder edp disabling to fix ivb MacBook Air

Unsurprisingly, various MacBooks failed.

Effectively the same has already been done in drm-intel-next-queued.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=74628
Tested-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>