Merge branch 'vrf-ipv6'

David Ahern says:

====================
net: VRF support in IPv6 stack

Initial support for VRF in IPv6 stack. Makes IPv6 functionality on par
with IPv4 -- ping, tcp client/server and udp client/server all work fine.
tcpdump on vrf device and external tap (e.g., host side tap device) shows
all packets with proper addresses. IPv6 does not need the source address
operation like IPv4. Verified vti6 works properly in my setup as does use
of an IPv6 address on the VRF device.

v3
- re-based to top of net-next (updates per net namespace changes by Eric)
- fixed dst_entry typecasts as requested by Dave
- added flags to inet6_rtm_getroute (IPv6 version of deaa0a6a)

v2
- fixed CONFIG_IPV6 dependency as questioned by Cong
  - if IPV6 is a module, kbuild ensures VRF is a module
  - if IPV6 is disabled IPV6 functionality is compiled out of VRF module
- addressed comments from Nik over IRC
  - removed duplicate call to netif_is_l3_master in l3mdev_rt6_dst_by_oif
  - changed allocation flag from GFP_ATOMIC to GFP_KERNEL since it is init time
  - added free of rt6i_pcpu
  - check_ipv6_frame returns false only if packet is NDISC type
====================

Signed-off-by: David S. Miller <davem@davemloft.net>