fix: Only keep latest ip/mac entry per machine
fix: Only keep latest ip/mac entry per machine

After the deployer sends out the introspection kernel to each cluster
node, the introspection kernel will ask for new dhcp addresses.
This can lead to multiple DHCPACK/DHCPRELEASE requests in syslog. We
now make sure any additional/duplicate DHCP messages for the same device
override the existing entry, instead of creating a new one.

Change-Id: I3151266a18885bfe4bb9bfe6a78a876307d62491

open-power-ref-design-toolkit/cluster-genesis,open-power-ref-design-toolkit/cluster-genesis