[coreboot] [PATCH] Update libpayload repo in readme

[Stefan Reinauer]

* Nils <njacobs8 at hetnet.nl> [110329 21:11]:
> Update repo path in libpayload readme.
> 
> Signed-off-by: Nils Jacobs <njacobs8 at hetnet.nl>
> 
> Thanks, Nils.

Thanks. r6469