mv643xx_eth: move mac_addr inside mv643xx_eth_platform_data

The information contained within platform_data should be self-contained.
Replace the pointer to a MAC address with the actual MAC address in
struct mv643xx_eth_platform_data.

Signed-off-by: Dale Farnsworth <dale@farnsworth.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>