net: hns3: fix for fraglist skb headlen not handling correctly

driver inclusion
category: bugfix
bugzilla: NA
CVE: NA

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when the fraglist skb headlen is larger than zero, current code
still handle the fraglist skb linear data as frag data, which may
cause tx error.

This patch adds a new DESC_TYPE_FRAGLIST_SKB type to handle the
mapping and unmapping of the fraglist skb linear data buffer.

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>