net: hns3: change the unit of GL value macro

Previously, driver used 2us as the GL unit. The time unit ethtool
command "-c" and "-C" use is 1us, so now the GL unit driver uses
actually is 1us.

This patch changes the unit of GL value macro from
2us to 1us.

Signed-off-by: Fuyun Liang <liangfuyun1@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>