tests/gnrc_ndp: Use NETOPT_MAX_DPU_SIZE
tests/gnrc_ndp: Use NETOPT_MAX_DPU_SIZE

Updated the test to use NETOPT_MAX_DPU_SIZE instead of the deprecated
NETOPT_MAX_PACKET_SIZE

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