boards/p-nucleo-wb55: remove useless custom define
boards/p-nucleo-wb55: remove useless custom define

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