drm/i915: Don't depend on encoder->new_crtc in intel_dp_compute_config()

	struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;

	struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);

	enum port port = dp_to_dig_port(intel_dp)->port;

	struct intel_crtc *intel_crtc = encoder->new_crtc;

	struct intel_crtc *intel_crtc = to_intel_crtc(pipe_config->base.crtc);

	struct intel_connector *intel_connector = intel_dp->attached_connector;

	int lane_count, clock;

	int min_lane_count = 1;