cpu/cc2538/cpu_conf: add OpenWSN conf
cpu/cc2538/cpu_conf: add OpenWSN conf

OTAkeys/RIOT,jasonatran/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,miri64/RIOT,ant9000/RIOT,OlegHahm/RIOT,RIOT-OS/RIOT,kYc0o/RIOT,miri64/RIOT,jasonatran/RIOT,kYc0o/RIOT,kaspar030/RIOT,kYc0o/RIOT,miri64/RIOT,OlegHahm/RIOT,miri64/RIOT,OTAkeys/RIOT,jasonatran/RIOT,kYc0o/RIOT,kaspar030/RIOT,ant9000/RIOT,jasonatran/RIOT,OlegHahm/RIOT,kYc0o/RIOT,OTAkeys/RIOT,ant9000/RIOT,OlegHahm/RIOT,kaspar030/RIOT,jasonatran/RIOT,OTAkeys/RIOT,OTAkeys/RIOT,ant9000/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,authmillenon/RIOT,OlegHahm/RIOT,miri64/RIOT,ant9000/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,kaspar030/RIOT