netfilter: nft_payload: do not update layer 4 checksum when mangling fragments

stable inclusion
from stable-v5.10.96
commit 94b23988c305f46619e273823865a0e650fbebb8
bugzilla: https://gitee.com/openeuler/kernel/issues/I55NWB

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=94b23988c305f46619e273823865a0e650fbebb8



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commit 4e1860a3 upstream.

IP fragments do not come with the transport header, hence skip bogus
layer 4 checksum updates.

Fixes: 18140969 ("netfilter: nft_payload: layer 4 checksum adjustment for pseudoheader fields")
Reported-and-tested-by: Steffen Weinreich <steve@weinreich.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Yu Liao <liaoyu15@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>