drivers/pca9633: make enum anonymous
drivers/pca9633: make enum anonymous

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