fix: Tune data interface MAC address collection (#365)
fix: Tune data interface MAC address collection (#365)

- Increase dhclient timeout and post-activation wait time to allow
  additional time for switch mac-address-table to be updated.

- Release any existing dhclient leases ('dhclient -r') before activate
  each interface. This is necessary if any interface successfully
  obtains a DHCP lease (previously would cause the _next_ interface to
  fail due to existing 'dhclient' process still running).
open-power-ref-design-toolkit/cluster-genesis,open-power-ref-design-toolkit/cluster-genesis