[IPV6] IP6TUNNEL: Use update_pmtu() of dst on xmit.
[IPV6] IP6TUNNEL: Use update_pmtu() of dst on xmit.

Signed-off-by: Yasuyuki Kozakai <0e1efae9b4af701edc66e09b95849e742dda8b01@toshiba.co.jp>
Signed-off-by: YOSHIFUJI Hideaki <948b80da4254122ea1e8973dd9930d46b7654cf3@linux-ipv6.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas