[libata] ahci: add ATI SB800 PCI IDs

ATI/AMD SB800 shares some device IDs with SB700,
and SB800 adds two more device IDs:0x4394,0x4395.

Signed-off-by: henry su <henry.su.ati@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>