net/neighbour: fix crash at dumping device-agnostic proxy entries

net/neighbour: fix crash at dumping device-agnostic proxy entries

Orabug: 22623860

[ Upstream commit 6adc5fd6a142c6e2c80574c1db0c7c17dedaa42e ]

Proxy entries could have null pointer to net-device.

Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Fixes: 84920c1420e2 ("net: Allow ipv6 proxies and arp proxies be shown with iproute2")
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit e08ca7be16f178988ccf95f96edf6eff5d89bb0a)
Signed-off-by: Dan Duval <dan.duval@oracle.com>