This enables recognition of the Intel E7210/6300ESB south
bridge and SATA/IDE controller.  With this, DMA works for
a SuperMicro P4SCi motherboard (the BIOS is set to the
"combined" mode rather than "SATA only" or "enhanced").

Without this patch, 9load complains but works ok, and
the kernel can do multi-sector transfers but not DMA,
resulting in vast slowness.