If DHCP relay config with the dhcp-relay-config-id is not already present, create a new DHCP relay config instance.
If it already exists, update the DHCP relay config instance with specified attributes.
If DHCP relay config with the dhcp-relay-config-id is not already present,
create a new DHCP relay config instance. If it already exists, replace
the DHCP relay config instance with this object.