drm/i915: use drm_for_each_connector_iter()

Drop legacy drm_for_each_connector() in favor of the race-free
drm_for_each_connector_iter().

Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170511191049.28944-4-gustavo@padovan.org

drivers/gpu/drm/i915/intel_display.c

@@ -11216,6 +11216,7 @@ static bool check_digital_port_conflicts(struct drm_atomic_state *state)
 {
 	struct drm_device *dev = state->dev;
 	struct drm_connector *connector;
+	struct drm_connector_list_iter conn_iter;
 	unsigned int used_ports = 0;
 	unsigned int used_mst_ports = 0;
 
@@ -11224,7 +11225,8 @@ static bool check_digital_port_conflicts(struct drm_atomic_state *state)
 	 * list to detect the problem on ddi platforms
 	 * where there's just one encoder per digital port.
 	 */
-	drm_for_each_connector(connector, dev) {
+	drm_connector_list_iter_begin(dev, &conn_iter);
+	drm_for_each_connector_iter(connector, &conn_iter) {
 		struct drm_connector_state *connector_state;
 		struct intel_encoder *encoder;
 
@@ -11263,6 +11265,7 @@ static bool check_digital_port_conflicts(struct drm_atomic_state *state)
 			break;
 		}
 	}
+	drm_connector_list_iter_end(&conn_iter);
 
 	/* can't mix MST and SST/HDMI on the same port */
 	if (used_ports & used_mst_ports)