drm/qxl: fix disabling extra monitors from client

To disable a monitor, a Spice client sends a monitor config with the
monitor resolution to 0x0.

However, before qxl_crtc_disable() is reached after the hotplug event,
it can happen that another monitor is reconfigured, and
qxl_send_monitors_config() is called with the old config, which will
re-enable the monitor on the client.

Reset config if monitor is found disconnected, during
drm_helper_hpd_irq_event().
Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

drivers/gpu/drm/qxl/qxl_display.c

@@ -803,7 +803,10 @@ static enum drm_connector_status qxl_conn_detect(
 		     qdev->client_monitors_config->count > output->index &&
 		     qxl_head_enabled(&qdev->client_monitors_config->heads[output->index]));
 
-	DRM_DEBUG("\n");
+	DRM_DEBUG("#%d connected: %d\n", output->index, connected);
+	if (!connected)
+		qxl_monitors_config_set(qdev, output->index, 0, 0, 0, 0, 0);
+
 	return connected ? connector_status_connected
 			 : connector_status_disconnected;
 }