[IPV6]: Fix SIOCCHGTUNNEL bug in IPv6 tunnels
[IPV6]: Fix SIOCCHGTUNNEL bug in IPv6 tunnels

A logic bug in tunnel lookup could result in duplicate tunnels when
changing an existing device.

Signed-off-by: Ville Nuorvala <3adf7238fd4aefcc1e7ff881944de5f536ac404a@tcs.hut.fi>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

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