makefiles/dfu: refactor configuration file
makefiles/dfu: refactor configuration file

miri64/RIOT,jasonatran/RIOT,yogo1212/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,yogo1212/RIOT,kaspar030/RIOT,ant9000/RIOT,RIOT-OS/RIOT,basilfx/RIOT,OlegHahm/RIOT,kYc0o/RIOT,yogo1212/RIOT,RIOT-OS/RIOT,miri64/RIOT,kYc0o/RIOT,basilfx/RIOT,kaspar030/RIOT,basilfx/RIOT,OTAkeys/RIOT,kYc0o/RIOT,yogo1212/RIOT,kaspar030/RIOT,OTAkeys/RIOT,jasonatran/RIOT,OlegHahm/RIOT,miri64/RIOT,miri64/RIOT,ant9000/RIOT,jasonatran/RIOT,ant9000/RIOT,authmillenon/RIOT,OTAkeys/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,basilfx/RIOT,kYc0o/RIOT,ant9000/RIOT,kaspar030/RIOT,yogo1212/RIOT,ant9000/RIOT,OTAkeys/RIOT,basilfx/RIOT,authmillenon/RIOT,kYc0o/RIOT,yogo1212/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,OlegHahm/RIOT,authmillenon/RIOT,OlegHahm/RIOT,kaspar030/RIOT,OTAkeys/RIOT,jasonatran/RIOT,miri64/RIOT,OlegHahm/RIOT,authmillenon/RIOT