compat: nf_defrag_ipv6: avoid/free clone operations.

compat: nf_defrag_ipv6: avoid/free clone operations.

Upstream commit:
    netfilter: ipv6: nf_defrag: avoid/free clone operations

    commit 6aafeef03b9d9ecf
    ("netfilter: push reasm skb through instead of original frag skbs")
    changed ipv6 defrag to not use the original skbs anymore.

    So rather than keeping the original skbs around just to discard them
    afterwards just use the original skbs directly for the fraglist of
    the newly assembled skb and remove the extra clone/free operations.

    The skb that completes the fragment queue is morphed into a the
    reassembled one instead, just like ipv4 defrag.

    openvswitch doesn't need any additional skb_morph magic anymore to deal
    with this situation so just remove that.

    A followup patch can then also remove the NF_HOOK (re)invocation in
    the ipv6 netfilter defrag hook.

    Cc: Joe Stringer <joestringer@nicira.com>
    Signed-off-by: Florian Westphal <fw@strlen.de>
    Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Upstream: 029f7f3b8701 ("netfilter: ipv6: nf_defrag: avoid/free clone operations")
Signed-off-by: Joe Stringer <joe@ovn.org>
Acked-by: Jesse Gross <jesse@kernel.org>