cpu/stm32f4: fix periph/adc resolution check
cpu/stm32f4: fix periph/adc resolution check

BytesGalore/RIOT,avmelnikoff/RIOT,OTAkeys/RIOT,aeneby/RIOT,gebart/RIOT,basilfx/RIOT,A-Paul/RIOT,biboc/RIOT,kbumsik/RIOT,lazytech-org/RIOT,rfuentess/RIOT,miri64/RIOT,x3ro/RIOT,mfrey/RIOT,rfuentess/RIOT,aeneby/RIOT,ant9000/RIOT,A-Paul/RIOT,josephnoir/RIOT,yogo1212/RIOT,OlegHahm/RIOT,cladmi/RIOT,LudwigOrtmann/RIOT,authmillenon/RIOT,LudwigOrtmann/RIOT,smlng/RIOT,kYc0o/RIOT,basilfx/RIOT,kaspar030/RIOT,LudwigKnuepfer/RIOT,kYc0o/RIOT,OTAkeys/RIOT,mtausig/RIOT,x3ro/RIOT,LudwigKnuepfer/RIOT,avmelnikoff/RIOT,neiljay/RIOT,mtausig/RIOT,authmillenon/RIOT,rfuentess/RIOT,cladmi/RIOT,OlegHahm/RIOT,ant9000/RIOT,A-Paul/RIOT,authmillenon/RIOT,mtausig/RIOT,miri64/RIOT,toonst/RIOT,miri64/RIOT,OlegHahm/RIOT,mtausig/RIOT,rfuentess/RIOT,OTAkeys/RIOT,authmillenon/RIOT,mfrey/RIOT,mfrey/RIOT,kYc0o/RIOT,ant9000/RIOT,smlng/RIOT,basilfx/RIOT,gebart/RIOT,biboc/RIOT,BytesGalore/RIOT,lazytech-org/RIOT,neiljay/RIOT,basilfx/RIOT,miri64/RIOT,x3ro/RIOT,biboc/RIOT,ant9000/RIOT,A-Paul/RIOT,aeneby/RIOT,cladmi/RIOT,A-Paul/RIOT,RIOT-OS/RIOT,RIOT-OS/RIOT,LudwigOrtmann/RIOT,toonst/RIOT,mfrey/RIOT,jasonatran/RIOT,kaspar030/RIOT,mtausig/RIOT,LudwigOrtmann/RIOT,toonst/RIOT,kYc0o/RIOT,jasonatran/RIOT,LudwigKnuepfer/RIOT,cladmi/RIOT,josephnoir/RIOT,avmelnikoff/RIOT,josephnoir/RIOT,LudwigOrtmann/RIOT,gebart/RIOT,gebart/RIOT,authmillenon/RIOT,kbumsik/RIOT,toonst/RIOT,kaspar030/RIOT,josephnoir/RIOT,LudwigOrtmann/RIOT,miri64/RIOT,kYc0o/RIOT,ant9000/RIOT,BytesGalore/RIOT,lazytech-org/RIOT,rfuentess/RIOT,yogo1212/RIOT,biboc/RIOT,RIOT-OS/RIOT,aeneby/RIOT,OlegHahm/RIOT,OTAkeys/RIOT,avmelnikoff/RIOT,neiljay/RIOT,lazytech-org/RIOT,smlng/RIOT,basilfx/RIOT,yogo1212/RIOT,OTAkeys/RIOT,gebart/RIOT,RIOT-OS/RIOT,BytesGalore/RIOT,toonst/RIOT,mfrey/RIOT,x3ro/RIOT,kbumsik/RIOT,kbumsik/RIOT,kbumsik/RIOT,jasonatran/RIOT,jasonatran/RIOT,kaspar030/RIOT,yogo1212/RIOT,aeneby/RIOT,authmillenon/RIOT,kaspar030/RIOT,BytesGalore/RIOT,lazytech-org/RIOT,cladmi/RIOT,jasonatran/RIOT,neiljay/RIOT,LudwigKnuepfer/RIOT,OlegHahm/RIOT,RIOT-OS/RIOT,smlng/RIOT,neiljay/RIOT,biboc/RIOT,yogo1212/RIOT,josephnoir/RIOT,LudwigKnuepfer/RIOT,smlng/RIOT,avmelnikoff/RIOT,x3ro/RIOT,yogo1212/RIOT