[coreboot] Selfboot error checking fix

[Myles Watson]

> Check the return value of ulzma, and quit instead of loading the next
> segment if there's an error.
>
> Size pointers 8 characters instead of 16 to beautify the common case
> where selfboot is loading something into memory below 4GB.
>
> Signed-off-by: Myles Watson <mylesgw at gmail.com>

> Acked-by: Stefan Reinauer <stepan at coresystems.de>

Rev 5602.

Thanks,
Myles