cpu/fe310: fix typo 'transfert' -> 'transfer'
cpu/fe310: fix typo 'transfert' -> 'transfer'

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