drivers/xbee: Fix reference to device from netif in send function
drivers/xbee: Fix reference to device from netif in send function

miri64/RIOT,jasonatran/RIOT,smlng/RIOT,OTAkeys/RIOT,OTAkeys/RIOT,authmillenon/RIOT,x3ro/RIOT,kaspar030/RIOT,ant9000/RIOT,OTAkeys/RIOT,ant9000/RIOT,authmillenon/RIOT,yogo1212/RIOT,RIOT-OS/RIOT,RIOT-OS/RIOT,x3ro/RIOT,RIOT-OS/RIOT,yogo1212/RIOT,yogo1212/RIOT,kYc0o/RIOT,jasonatran/RIOT,OlegHahm/RIOT,smlng/RIOT,smlng/RIOT,yogo1212/RIOT,miri64/RIOT,basilfx/RIOT,kaspar030/RIOT,jasonatran/RIOT,OlegHahm/RIOT,miri64/RIOT,kaspar030/RIOT,toonst/RIOT,yogo1212/RIOT,kYc0o/RIOT,toonst/RIOT,x3ro/RIOT,smlng/RIOT,authmillenon/RIOT,yogo1212/RIOT,OTAkeys/RIOT,ant9000/RIOT,OTAkeys/RIOT,basilfx/RIOT,kYc0o/RIOT,kYc0o/RIOT,miri64/RIOT,ant9000/RIOT,x3ro/RIOT,ant9000/RIOT,x3ro/RIOT,smlng/RIOT,kYc0o/RIOT,jasonatran/RIOT,kaspar030/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,jasonatran/RIOT,toonst/RIOT,OlegHahm/RIOT,OlegHahm/RIOT,toonst/RIOT,basilfx/RIOT,toonst/RIOT,basilfx/RIOT,OlegHahm/RIOT,basilfx/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,miri64/RIOT