natsemi: Add support for using MII port with no PHY

natsemi: Add support for using MII port with no PHY

This patch provides code paths which allow the natsemi driver to use the
external MII port on the chip but ignore any PHYs that may be attached to it.
The link state will be left as it was when the driver started and can be
configured via ethtool.  Any PHYs that are present can be accessed via the MII
ioctl()s.

This is useful for systems where the device is connected without a PHY
or where either information or actions outside the scope of the driver
are required in order to use the PHYs.

Signed-Off-By: Mark Brown <broonie@sirena.org.uk>
Signed-off-by: Jeff Garzik <jeff@garzik.org>