addons: set addrgenmode to none for vrrp macvlan

addons: set addrgenmode to none for vrrp macvlan

A VRRP macvlan interface should only have addresses matching the
VIP defined by the user.  This change ensures we set ipv6 addrgenmode
to none, that way there won't be any unexpected (from user standpoint)
ipv6 link-local addresses to cause confusion or erroneous Type-2 EVPN
routes (in the case of advertise-default-gw with VRRP instead of VRR)
that advertise IP addresses that don't represent a VIP.

Signed-off-by: Trey Aspelund <taspelund@nvidia.com>
Signed-off-by: Julien Fortin <jfortin@nvidia.com>