addons: addressvirtual: if device is VRF slave check vrf route table

addons: addressvirtual: if device is VRF slave check vrf route table

auto bridge
iface bridge
      bridge-vlan-aware yes
      bridge-ports swp2

auto bridge.2
iface bridge.2
      address 10.254.1.2/24
      address 2a03:25e0:254:1::2/64
      address-virtual 00:00:5e:00:01:01 10.254.1.1/24 2a03:25e0:254:1::1/64 fe80::1/64
      vrf blue

auto blue
iface blue
      vrf-table auto

$ ifreload -a -v
...
info: executing /bin/ip route get 10.254.1.0/24 vrf blue
...
$

Reviewed-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: Julien Fortin <julien@cumulusnetworks.com>