[NETNS][IPV6]: Add ipv6 structure for netns.

Like the ipv4 part, this patch adds an ipv6 structure in the net
structure to aggregate the different resources to make ipv6 per
namespace.

Signed-off-by: Daniel Lezcano <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
2 files changed