Add the combined mode for ATI SB700

Add the combined mode for ATI SB700

Besides those modes in ATI SB600 SATA controller, ATI SB700 supports one
more mode:the combined mode.

The combined mode is a Legacy IDE mode used for compatibility with some old
OS without AHCI driver, but now it is not necessary for Linux since the
kernel has supported AHCI.

Signed-off-by: Luugi Marsan <[email protected]>
Cc: Jeff Garzik <[email protected]>
Cc: Tejun Heo <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Jeff Garzik <[email protected]>