net: hns3: fix flow control configure issue for fibre port

driver inclusion
category: bugfix
bugzilla: NA
CVE: NA

Flow control autoneg is unsupported for fibre port. It takes no
effect for flow control when restart autoneg. This patch fixes
it, return -EOPNOTSUPP whn user tries to enable flow control
autoneg.

Feature or Bugfix:Bugfix

Signed-off-by: shenjian (K) <shenjian15@huawei.com>
Reviewed-by: lipeng <lipeng321@huawei.com>
Reviewed-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>