net: hns3: Support two vlan header when setting mtu

net: hns3: Support two vlan header when setting mtu

BugLink: https://bugs.launchpad.net/bugs/1810457
This patch adds supports for two vlan header when setting mtu.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit a0b4371751bf836fb438877c981bda733f918988)
Signed-off-by: dann frazier <dann.frazier@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>