The reason behind this change is that as soon as we delete
the last ipv6 address of an interface we also lose the
/proc/sys/net/ipv6/conf/<interface> directory. This seems to be a
usability problem for me.

I don't see any reason why we should shutdown ipv6 on that interface in
such cases.

Cc: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>