drivers/slipdev: use netdev_set_notsup()
drivers/slipdev: use netdev_set_notsup()

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