sys/timex: Add Kconfig support
sys/timex: Add Kconfig support

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