efinet + bootp: add net_bootp6 command supporting dhcpv6

efinet + bootp: add net_bootp6 command supporting dhcpv6

Implement new net_bootp6 command for IPv6 network auto configuration via
the DHCPv6 protocol (RFC3315).

Signed-off-by: Peter Jones <pjones@redhat.com>
Co-authored-by: Michael Chang <mchang@suse.com>
Signed-off-by: Michael Chang <mchang@suse.com>
Signed-off-by: Ken Lin <ken.lin@hpe.com>
Co-authored-by: Robbie Harwood <rharwood@redhat.com>
Signed-off-by: Robbie Harwood <rharwood@redhat.com>
Gbp-Pq: Topic network
Gbp-Pq: Name bootp-new-net_bootp6-command.patch