cpu/cc2538/periph/timer: cleanup styling
cpu/cc2538/periph/timer: cleanup styling

kYc0o/RIOT,OlegHahm/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,miri64/RIOT,OTAkeys/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,ant9000/RIOT,kaspar030/RIOT,yogo1212/RIOT,kaspar030/RIOT,yogo1212/RIOT,yogo1212/RIOT,jasonatran/RIOT,OlegHahm/RIOT,miri64/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,miri64/RIOT,OTAkeys/RIOT,OlegHahm/RIOT,yogo1212/RIOT,basilfx/RIOT,jasonatran/RIOT,authmillenon/RIOT,yogo1212/RIOT,authmillenon/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT,OlegHahm/RIOT,kYc0o/RIOT,kYc0o/RIOT,basilfx/RIOT,basilfx/RIOT,miri64/RIOT,kaspar030/RIOT,ant9000/RIOT,kaspar030/RIOT,OTAkeys/RIOT,miri64/RIOT,RIOT-OS/RIOT,basilfx/RIOT,authmillenon/RIOT,kaspar030/RIOT,kYc0o/RIOT,ant9000/RIOT,kYc0o/RIOT,ant9000/RIOT,jasonatran/RIOT,OTAkeys/RIOT,jasonatran/RIOT,yogo1212/RIOT,basilfx/RIOT,ant9000/RIOT,OTAkeys/RIOT