ahci: Blacklist HP Compaq 6720s that spins off disks during ACPI power off

Blacklist HP Compaq 6720s so that it doesn't play a "spin down,
spin up, spin down" ping-pong with the hard disk during system
power off.

Signed-off-by: Maciej Rutecki <maciej.rutecki@gmail.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/ahci.c

@@ -2565,6 +2565,15 @@ static bool ahci_broken_system_poweroff(struct pci_dev *pdev)
 			/* PCI slot number of the controller */
 			.driver_data = (void *)0x1FUL,
 		},
+		{
+			.ident = "HP Compaq 6720s",
+			.matches = {
+				DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
+				DMI_MATCH(DMI_PRODUCT_NAME, "HP Compaq 6720s"),
+			},
+			/* PCI slot number of the controller */
+			.driver_data = (void *)0x1FUL,
+		},
 
 		{ }	/* terminate list */
 	};