drm/i915: fix missed hunk after GT access breakage

Upon some code refactoring, a hunk was missed. This was fixed for
next, but missed the current trees, and hasn't yet been merged by Dave
Airlie. It is fixed in:
commit 907b28c5
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Fri Jul 19 20:36:52 2013 +0100

    drm/i915: Colocate all GT access routines in the same file

It is introduced by:
commit 181d1b9e


Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Sun Jul 21 13:16:24 2013 +0200

    drm/i915: fix up gt init sequence fallout

Reported-by: Dave Jones <davej@redhat.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>