As far as I can remember, I was going to disable privacy extensions
on all "tunnel" interfaces.  Disable it on ip6-ip6 interface as well.

Also, just remove ifdefs for SIT for simplicity.
Signed-off-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>