drm/i915: Only kick out vesafb if we takeover the fbcon with KMS

Otherwise we may remove the only console for a nomodeset system.

We became more aggressive in our kicking with
commit e188719a
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Tue Jun 12 11:28:17 2012 +0200

    drm/i915: kick any firmware framebuffers before claiming the gtt

Reported-and-tested-by:  <monnier@iro.umontreal.ca>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=54615


Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@vger.kernel.org # v3.6
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>