drm/i915: Set connector_state->connector using the helper.

The atomic helper sets connector_state->connector, which the i915
code didn't. This will become a problem when we start using it.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1451908400-25147-1-git-send-email-maarten.lankhorst@linux.intel.com


Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>