stm32l0/pm: clear wakeup flags when setting STOP mode.
stm32l0/pm: clear wakeup flags when setting STOP mode.

josephnoir/RIOT,rfuentess/RIOT,basilfx/RIOT,RIOT-OS/RIOT,lazytech-org/RIOT,kYc0o/RIOT,mtausig/RIOT,lazytech-org/RIOT,jasonatran/RIOT,kaspar030/RIOT,ant9000/RIOT,OlegHahm/RIOT,jasonatran/RIOT,yogo1212/RIOT,yogo1212/RIOT,authmillenon/RIOT,cladmi/RIOT,kYc0o/RIOT,cladmi/RIOT,OTAkeys/RIOT,josephnoir/RIOT,smlng/RIOT,miri64/RIOT,yogo1212/RIOT,cladmi/RIOT,kaspar030/RIOT,x3ro/RIOT,RIOT-OS/RIOT,yogo1212/RIOT,aeneby/RIOT,toonst/RIOT,kYc0o/RIOT,ant9000/RIOT,authmillenon/RIOT,mtausig/RIOT,josephnoir/RIOT,jasonatran/RIOT,mfrey/RIOT,basilfx/RIOT,rfuentess/RIOT,authmillenon/RIOT,kYc0o/RIOT,jasonatran/RIOT,authmillenon/RIOT,cladmi/RIOT,josephnoir/RIOT,OlegHahm/RIOT,ant9000/RIOT,smlng/RIOT,x3ro/RIOT,cladmi/RIOT,OTAkeys/RIOT,mfrey/RIOT,mtausig/RIOT,aeneby/RIOT,smlng/RIOT,OTAkeys/RIOT,josephnoir/RIOT,toonst/RIOT,mtausig/RIOT,aeneby/RIOT,toonst/RIOT,OlegHahm/RIOT,lazytech-org/RIOT,lazytech-org/RIOT,jasonatran/RIOT,basilfx/RIOT,kaspar030/RIOT,kYc0o/RIOT,smlng/RIOT,ant9000/RIOT,miri64/RIOT,rfuentess/RIOT,mfrey/RIOT,yogo1212/RIOT,toonst/RIOT,lazytech-org/RIOT,x3ro/RIOT,OlegHahm/RIOT,authmillenon/RIOT,OlegHahm/RIOT,miri64/RIOT,rfuentess/RIOT,basilfx/RIOT,kaspar030/RIOT,x3ro/RIOT,aeneby/RIOT,mfrey/RIOT,authmillenon/RIOT,rfuentess/RIOT,OTAkeys/RIOT,OTAkeys/RIOT,RIOT-OS/RIOT,aeneby/RIOT,kaspar030/RIOT,RIOT-OS/RIOT,miri64/RIOT,mtausig/RIOT,RIOT-OS/RIOT,yogo1212/RIOT,toonst/RIOT,x3ro/RIOT,ant9000/RIOT,basilfx/RIOT,miri64/RIOT,mfrey/RIOT,smlng/RIOT