[coreboot] A little patch to fix rs690 bug:

[Li, Maggie]

Hi,

Attachment is a little patch to fix rs690 bug about GPPSB configuration.
Signed-off-by:  Maggie Li 
Reviewed-by:    Zheng Bao <[e-mail]  >
Please check it, thanks.
 <<fix_rs690_bug.patch>> 
Best regards
Maggie li