Add the function to set PHY min and max linkrate through
sysfs interface.
Signed-off-by: NXiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: NJohn Garry <john.garry@huawei.com>
Reviewed-by: NZhangfei Gao <zhangfei.gao@linaro.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>