cpu/nrf52/i2c: use static mutex initializtion
cpu/nrf52/i2c: use static mutex initializtion

x3ro/RIOT,mtausig/RIOT,kaspar030/RIOT,LudwigOrtmann/RIOT,basilfx/RIOT,ant9000/RIOT,basilfx/RIOT,gebart/RIOT,cladmi/RIOT,mtausig/RIOT,smlng/RIOT,neiljay/RIOT,RIOT-OS/RIOT,neiljay/RIOT,mfrey/RIOT,OlegHahm/RIOT,kYc0o/RIOT,smlng/RIOT,gebart/RIOT,kYc0o/RIOT,neiljay/RIOT,x3ro/RIOT,smlng/RIOT,mfrey/RIOT,kbumsik/RIOT,mfrey/RIOT,smlng/RIOT,BytesGalore/RIOT,josephnoir/RIOT,biboc/RIOT,mfrey/RIOT,basilfx/RIOT,josephnoir/RIOT,ant9000/RIOT,LudwigOrtmann/RIOT,BytesGalore/RIOT,rfuentess/RIOT,rfuentess/RIOT,yogo1212/RIOT,jasonatran/RIOT,lazytech-org/RIOT,kbumsik/RIOT,x3ro/RIOT,cladmi/RIOT,gebart/RIOT,authmillenon/RIOT,LudwigKnuepfer/RIOT,OlegHahm/RIOT,avmelnikoff/RIOT,LudwigKnuepfer/RIOT,kbumsik/RIOT,mtausig/RIOT,kYc0o/RIOT,toonst/RIOT,BytesGalore/RIOT,miri64/RIOT,avmelnikoff/RIOT,authmillenon/RIOT,kaspar030/RIOT,aeneby/RIOT,ant9000/RIOT,OTAkeys/RIOT,authmillenon/RIOT,lazytech-org/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,biboc/RIOT,mtausig/RIOT,authmillenon/RIOT,cladmi/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,gebart/RIOT,OTAkeys/RIOT,miri64/RIOT,lazytech-org/RIOT,OlegHahm/RIOT,kaspar030/RIOT,ant9000/RIOT,kbumsik/RIOT,josephnoir/RIOT,cladmi/RIOT,mtausig/RIOT,miri64/RIOT,kaspar030/RIOT,toonst/RIOT,avmelnikoff/RIOT,A-Paul/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,LudwigOrtmann/RIOT,neiljay/RIOT,rfuentess/RIOT,avmelnikoff/RIOT,LudwigOrtmann/RIOT,lazytech-org/RIOT,rfuentess/RIOT,A-Paul/RIOT,biboc/RIOT,miri64/RIOT,yogo1212/RIOT,basilfx/RIOT,miri64/RIOT,A-Paul/RIOT,jasonatran/RIOT,yogo1212/RIOT,LudwigOrtmann/RIOT,toonst/RIOT,smlng/RIOT,BytesGalore/RIOT,OlegHahm/RIOT,neiljay/RIOT,LudwigKnuepfer/RIOT,yogo1212/RIOT,gebart/RIOT,yogo1212/RIOT,kYc0o/RIOT,A-Paul/RIOT,biboc/RIOT,rfuentess/RIOT,A-Paul/RIOT,yogo1212/RIOT,avmelnikoff/RIOT,basilfx/RIOT,OTAkeys/RIOT,aeneby/RIOT,aeneby/RIOT,authmillenon/RIOT,josephnoir/RIOT,aeneby/RIOT,ant9000/RIOT,LudwigOrtmann/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,x3ro/RIOT,LudwigKnuepfer/RIOT,LudwigKnuepfer/RIOT,jasonatran/RIOT,OTAkeys/RIOT,lazytech-org/RIOT,OlegHahm/RIOT,x3ro/RIOT,kbumsik/RIOT,mfrey/RIOT,josephnoir/RIOT,aeneby/RIOT,BytesGalore/RIOT,cladmi/RIOT,jasonatran/RIOT,toonst/RIOT,biboc/RIOT,toonst/RIOT