net: hns3: add 8 BD limit for tx flow

net: hns3: add 8 BD limit for tx flow

BugLink: https://bugs.launchpad.net/bugs/1819535
A single transmit packet can span up to 8 descriptors according
to the HW limit. If a skb has more than 8 frags, driver uses
skb_copy to get a new skb which has less frags.

Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 51e8439f34962794f6c5010a44893fe58450b8df)
Signed-off-by: dann frazier <dann.frazier@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>