ARM: shmobile: Add SMSC ethernet chip to KZM9D DT reference

Add support for the SMSC ethernet controller found
on the KZM9D board to the KZM9D DT Reference code.

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>