Some SATA controllers embedded in ATI IXPs seem to have broken
SATA_IRQ bit in their bmdma2 registers which is always stuck at 1.
This makes the driver believe that there has been a hotplug event and
freeze the port whenever there's an interrupt thus failing all
commands.

This patch disables SATA_IRQ for those controllers.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>