[POWERPC] Add initial iomega StorCenter board port.

Use cuImage bootwrapper until U-Boot port is completed.
Derived heavily from Linkstation port.

Signed-off-by: Jon Loeliger <jdl@freescale.com>
Acked-by: Andy Wilcox <andy@protium.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>