cpu/stm32/periph/adc_l4: removes ADC configuration loading
cpu/stm32/periph/adc_l4: removes ADC configuration loading

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