drm/i915: Allocate connector state together with the connectors

Connector states were being allocated in intel_setup_outputs() in loop
over all connectors. That meant hot-added connectors would have a NULL
state. Since the change to use a struct drm_atomic_state for the legacy
modeset, connector states are necessary for the i915 driver to function
properly, so that would lead to oopses.

v2: Fix test for intel_connector_init() success in lvds and sdvo (PRTS)

Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reported-and-tested-by: Nicolas Kalkhof <nkalkhof@web.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>