drivers/periph_common/timer: protect timer_set from IRQs
drivers/periph_common/timer: protect timer_set from IRQs

OlegHahm/RIOT,RIOT-OS/RIOT,x3ro/RIOT,yogo1212/RIOT,yogo1212/RIOT,kYc0o/RIOT,jasonatran/RIOT,kYc0o/RIOT,x3ro/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,toonst/RIOT,authmillenon/RIOT,yogo1212/RIOT,ant9000/RIOT,mtausig/RIOT,authmillenon/RIOT,basilfx/RIOT,basilfx/RIOT,jasonatran/RIOT,miri64/RIOT,jasonatran/RIOT,mtausig/RIOT,OTAkeys/RIOT,x3ro/RIOT,ant9000/RIOT,smlng/RIOT,toonst/RIOT,smlng/RIOT,toonst/RIOT,OlegHahm/RIOT,basilfx/RIOT,OTAkeys/RIOT,toonst/RIOT,miri64/RIOT,kaspar030/RIOT,kaspar030/RIOT,basilfx/RIOT,yogo1212/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,OlegHahm/RIOT,yogo1212/RIOT,toonst/RIOT,miri64/RIOT,yogo1212/RIOT,jasonatran/RIOT,kYc0o/RIOT,authmillenon/RIOT,smlng/RIOT,x3ro/RIOT,smlng/RIOT,miri64/RIOT,kaspar030/RIOT,ant9000/RIOT,basilfx/RIOT,kaspar030/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT,x3ro/RIOT,mtausig/RIOT,authmillenon/RIOT,jasonatran/RIOT,OTAkeys/RIOT,mtausig/RIOT,smlng/RIOT,authmillenon/RIOT,mtausig/RIOT,miri64/RIOT,ant9000/RIOT,kYc0o/RIOT,OlegHahm/RIOT,OTAkeys/RIOT,OTAkeys/RIOT,RIOT-OS/RIOT,ant9000/RIOT