mdio bus frequency is going to be configurable at boottime by a property
in DT now, so add a description to it.
Signed-off-by: NAndy Chiu <andy.chiu@sifive.com>
Reviewed-by: NGreentime Hu <greentime.hu@sifive.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>