net: dsa: mv88e6xxx: pass compatible info

After allocating the chip structure, pass it a compatible info pointer.

The compatible info structure will be used later to describe how to
access the switch registers and where to read the switch ID.

For the standard MDIO probe, get it from the device node data. For the
legacy DSA driver probing, pass it the 88E6085 info.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>