kirkwood: add support for Iomega iConnect board

Add support for new board iConnect from Iomega.

More information about the device can be found here:

http://go.iomega.com/en/products/network-storage-desktop/wireless-data-station/network-hard-drive-iconnect/?partner=4735



Signed-off-by: Luka Perkov <uboot@lukaperkov.net>
Tested-by: Wojciech Dubowik <wojciech.dubowik@neratec.com>
Tested-by: Tim Fletcher <tim@night-shade.org.uk>