test: change used RPL IP address
test: change used RPL IP address

The dtls server is using 0xaaa::0200:0000:0000:0001 as its default ip
address.

Signed-off-by: Hauke Mehrtens <435ddd46dc66c007a1fa20144c823d37e0d23436@hauke-m.de>

spark/tinydtls,OlegHahm/tinydtls,yunus/TinyDTLS-WebID,nmacs/tinydtls,thecodemaiden/tinydtls-fork,nmacs/tinydtls,fvdnabee/tinydtls,thecodemaiden/tinydtls-fork,nmacs/tinydtls,fvdnabee/tinydtls,OlegHahm/tinydtls,nmacs/tinydtls,jvermillard/tinydtls,fvdnabee/tinydtls,jvermillard/tinydtls,OlegHahm/tinydtls,spark/tinydtls,spark/tinydtls,jvermillard/tinydtls,yunus/TinyDTLS-WebID,yunus/TinyDTLS-WebID,thecodemaiden/tinydtls-fork