drm: don't poll forced connectors

Otherwise if the detect callback reports a different state than what
the user forced (rather likely), we continously annoy userspace about
a hotplug uevent.
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_crtc_helper.c

@@ -965,6 +965,10 @@ static void output_poll_execute(struct work_struct *work)
 	mutex_lock(&dev->mode_config.mutex);
 	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
 
+		/* Ignore forced connectors. */
+		if (connector->force)
+			continue;
+
 		/* Ignore HPD capable connectors and connectors where we don't
 		 * want any hotplug detection at all for polling. */
 		if (!connector->polled || connector->polled == DRM_CONNECTOR_POLL_HPD)