drm/vmwgfx: Send a hotplug event at master_set

Make sure drm clients (mostly the X server) are communicated the current
layout when switched in.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>

drivers/gpu/drm/vmwgfx/vmwgfx_drv.c

@@ -1204,6 +1204,7 @@ static int vmw_master_set(struct drm_device *dev,
 	}
 
 	dev_priv->active_master = vmaster;
+	drm_sysfs_hotplug_event(dev);
 
 	return 0;
 }