The new flowlabels should be inserted into the sock list
under the ip6_sk_fl_lock. This was lost in one place.

This list is naturally protected with the socket lock, but
the fl6_sock_lookup() is called without it, so another
protection is required.
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>