Tunneling: use IP Tunnel stats APIs.

Use common function get calculate rtnl_link_stats64 stats.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc net/ipv4/Kconfig
Simple merge

diff --cc net/ipv4/ip_vti.c
Simple merge

diff --cc net/ipv6/Kconfig
Simple merge

diff --cc net/ipv6/ip6_gre.c
Simple merge

diff --cc net/ipv6/sit.c
Simple merge