[ARM] Orion: common platform setup for Gigabit Ethernet port

The Orion Ethernet port is the same port used in the Discovery
family (MV643XX). This patch include the common platform_device
stuff according to the existing mv643xx_eth conventions.

Signed-off-by: Tzachi Perelstein <tzachi@marvell.com>
Reviewed-by: Lennert Buytenhek <buytenh@marvell.com>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>