ata_piix: fix suspend/resume for some TOSHIBA laptops

ACPI implementations in several TOSHIBA laptops are weird and burn cpu
cycles for tens of seconds while trying to suspend if the PCI device
for the ATA controller is disabled when the ACPI suspend is called.

This patch uses DMI to match those machines and bypass device disable
on those machines during suspend.  As the device needs to be put into
enabled state on resume without affecting PCI enable count, matching
resume callback uses __pci_reenable_device().

This bug is reported in bugzilla bug 7780.

  http://bugzilla.kernel.org/show_bug.cgi?id=7780

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

include/linux/libata.h

@@ -216,6 +216,8 @@ enum {
 	ATA_HOST_SIMPLEX	= (1 << 0),	/* Host is simplex, one DMA channel per host only */
 	ATA_HOST_STARTED	= (1 << 1),	/* Host started */
 
+	/* bits 24:31 of host->flags are reserved for LLD specific flags */
+
 	/* various lengths of time */
 	ATA_TMOUT_BOOT		= 30 * HZ,	/* heuristic */
 	ATA_TMOUT_BOOT_QUICK	= 7 * HZ,	/* heuristic */