If rdisc6 is available, a node using this element will loops until
DIB_DHCP_TIMEOUT is reached because of a missing 'break' when rdisc6
return code is 0.
This will mark the dhcp-interface@.service unit as failed (because it
has the same timeout) and not bring any network interface online.
Change-Id: I034dcda94d765f236950ebcbee36789f5bdc515f
Closes-Bug: #1854717
Signed-off-by: Hervé Rousseau <hroussea@cern.ch>
