net: hns3: additional fix for fraglist handling

driver inclusion
category: bugfix
bugzilla: NA
CVE: NA

-----------------------------

This patch adds additional handling which is missing in
commmit 108d36fe5d479dd3:

And this patch need to be merged with the above commit when
upstreaming.

Fixes: 108d36fe5d479dd3
("net: hns3: fix for fraglist skb headlen not handling correctly")

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Reviewed-by: Peng Li <lipeng321@huawei.com>
Reviewed-by: Weiwei Deng <dengweiwei@huawei.com>
Reviewed-by: Zhaohui Zhong <zhongzhaohui@huawei.com>
Reviewed-by: Junxing Chen <chenjunxin1@huawei.com>
Reviewed-by: Zhong Zhaohui <zhongzhaohui@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>