sh_eth: create initial ID table

We are trying to get away from the current driver's scheme of identifying a SoC
based on #ifdef's and the platform device ID table matching seems to be a good
replacement -- we can use the 'driver_data' field of 'struct platform_device_id'
as a pointer to a 'struct sh_eth_cpu_data'. Start by creating the initial table
with driver's name as the only entry without the driver data. Check  the driver
data in the probe() method and if it's not NULL override 'mdp->cd' from it.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>