xfa: remove duplicate "const" from _XFA_CONST
xfa: remove duplicate "const" from _XFA_CONST

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