gfxboot is now loaded via a COM32 module. If you used a line like gfxboot bootlogo before in isolinux.cfg or syslinux.cfg, change this to ui gfxboot bootlogo and add /usr/share/syslinux/gfxboot.c32 to your boot directory (the one where the config file is). You can also use ui gfxboot bootlogo message and remove the display message line. The 'message' file will be shown when you leave the gfxboot module (or it couldn't be started). This also means that gfxboot now works with other syslinux variants like pxelinux or extlinux.