cpu/stm32/periph/pwm: some bugfixes...
cpu/stm32/periph/pwm: some bugfixes...

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