net/ipv6: Put lwtstate when destroying fib6_info

net/ipv6: Put lwtstate when destroying fib6_info

[ Upstream commit 80f1a0f4e0cd4bfc8a74fc1c39843a6e7b206b95 ]

Prior to the introduction of fib6_info lwtstate was managed by the dst
code. With fib6_info releasing lwtstate needs to be done when the struct
is freed.

Fixes: 93531c674315 ("net/ipv6: separate handling of FIB entries from dst based routes")
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>