[POWERPC] mpc5200: Fix incorrect compatible string for the mdio node
The MDIO node in the lite5200b.dts file needs to also claim compatibility
with the older mpc5200 chip. Otherwise the driver won't find the device.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Paul Mackerras <paulus@samba.org>
authored by Grant Likely and committed by Paul Mackerras 5492a7e4 eff2f1ec