[PATCH] DT: add MDIO node for FMan node

[Joakim Tjernlund]

> >
> > The TBI implements transmit/receive portions of PCS, it's not used in
> > Linux. The PCS on Fman V3 are not just for SGMII, it has more
> > implementations, it's used in Linux.

It is used for PHY less mode(aka fixed PHY) and needs to be exposed to
linux so it is possible to select SGMII/1000BASE-X, AutoNeg etc.

> 
> The device tree is about the hardware, not what's used in Linux.
> 
> -Scott