stm32_common/gpio: remove unused guard
stm32_common/gpio: remove unused guard

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