[coreboot] Support for the new siemens sitemp_g1p1 mainboard

[Josef Kellermann]

Attached patch provides support for the siemens sitemp_g1p1 mainboard.
This board is similar to the amd dbm690t. I adapt the code from dbm690t 
according
  to customer requirement specification.
I have been testing Linux as well as Windows XP booting on this board.

Signed-off-by: Josef Kellermann