drm/i915: Fix dereferencing invalid connectors in is_crtc_connector_off()

In commit e3de42b6
Author: Imre Deak <imre.deak@intel.com>
Date:   Fri May 3 19:44:07 2013 +0200

    drm/i915: force full modeset if the connector is in DPMS OFF mode

a new function was added that walked over the set of connectors to see
if any of the currently associated CRTC was switched off. This function
walked an array of connectors, rather than the array of pointers to
connectors contained in the drm_mode_set - i.e. it was dereferencing far
past the end of the first connector. This only becomes an issue if we
attempt to use a clone mode (i.e. more than one connector per CRTC) such
that set->num_connectors > 1.

Reported-by: Timo Aaltonen <tjaalton@ubuntu.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=65927


Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Egbert Eich <eich@suse.de>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>