[U-Boot] Add support for Mini2440

[Gabriel Huau]

Hi all,

This is a first patch to introduce the support of the Mini2440. It's a
board based on the S3C2440, arm920t. I based the support on the code of
BusError (old version of u-boot).

I have a few work to do again, like some clean up in the configuration
file. Currently, with this patch, we can boot from NOR and the network
is available (tftp, dhcp, ...). Boot from NAND will be the next step
(and laters MMC). 

Best regards,