drm/i915: Don't manually add connectors and planes state

drm_atomic_commit() call chain already takes care of adding
connectors and planes, so lets no add then manually if not changing
their states.

drm_atomic_commit()
        drm_atomic_check_only()
                config->funcs->atomic_check()/intel_atomic_check()
                        drm_atomic_helper_check()
                                drm_atomic_helper_check_modeset()
                                        for_each_oldnew_crtc_in_state()
                                                drm_atomic_add_affected_connectors()
                                                drm_atomic_add_affected_planes()

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Lyude Paul <lyude@redhat.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190302003349.19189-2-jose.souza@intel.com