net: hns3: Add support for serdes loopback selftest

net: hns3: Add support for serdes loopback selftest

BugLink: https://bugs.launchpad.net/bugs/1787477
This patch adds support for serdes loopback selftest in hns3
driver.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 5fd50ac38fb66451672b75f8d143dbef6081dd3a)
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>