If a 32 bits l2tpv3 frame cookie MSB if set to 1, the cast to uint64_t
cookie will spread 1 to the four most significant bytes.
Then the condition (cookie != s->rx_cookie) becomes false.
Signed-off-by: NAlexis Dambricourt <alexis.dambricourt@gmail.com>
Signed-off-by: NJason Wang <jasowang@redhat.com>