drm/i915: Make encoder->compute_config take the connector state

Some places iterate over connector_state to find the right
connector, pass it along as argument.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470755054-32699-7-git-send-email-maarten.lankhorst@linux.intel.com


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