makefiles/kconfig: add pkg-prepare as menuconfig dependency
makefiles/kconfig: add pkg-prepare as menuconfig dependency

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