drivers/encx24j600: avoid explicit cast to netdev
drivers/encx24j600: avoid explicit cast to netdev

authmillenon/RIOT,OTAkeys/RIOT,RIOT-OS/RIOT,miri64/RIOT,OlegHahm/RIOT,ant9000/RIOT,kaspar030/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,kaspar030/RIOT,OlegHahm/RIOT,jasonatran/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,kaspar030/RIOT,miri64/RIOT,miri64/RIOT,authmillenon/RIOT,OTAkeys/RIOT,kYc0o/RIOT,ant9000/RIOT,kYc0o/RIOT,miri64/RIOT,OTAkeys/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT,OTAkeys/RIOT,ant9000/RIOT,ant9000/RIOT,kYc0o/RIOT,authmillenon/RIOT,authmillenon/RIOT,OlegHahm/RIOT,kaspar030/RIOT,authmillenon/RIOT,kYc0o/RIOT,ant9000/RIOT,jasonatran/RIOT,authmillenon/RIOT,OlegHahm/RIOT,jasonatran/RIOT,kYc0o/RIOT,miri64/RIOT,jasonatran/RIOT