tcp_comp: Add dpkt to save decompressed skb

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I48H9Z?from=project-issue


CVE: NA

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In order to separate the compressed data and decompressed data, this patch adds
dpkt to tcp_comp_context_rx, dpkt is used to save decompressed skb.

Signed-off-by: Wang Yufen <wangyufen@huawei.com>
Reviewed-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>