net: hns: Optimise the code in hns_mdio_wait_ready()

This patch fixes the code to clear pclint warning/info.

Reported-by: Ping Zhang <zhangping5@huawei.com>
Signed-off-by: Kejian Yan <yankejian@huawei.com>
Reviewed-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>