ssb: Look for SPROM at different offset on higher rev CC

Our offset handling becomes even a little more hackish now. For some reason I
do not understand all offsets as inrelative. It assumes base offset is 0x1000
but it will work for now as we make offsets relative anyway by removing base
0x1000. Should be cleaner however.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>