[libata] Prevent interface errors with Seagate FreeAgent GoFlex

When using my Seagate FreeAgent GoFlex eSATAp external disk enclosure,
interface errors are always seen until 1.5Gbps is negotiated [1]. This
occurs using any disk in the enclosure, and when the disk is connected
directly with a generic passive eSATAp cable, we see stable 3Gbps
operation as expected.

Blacklist 3Gbps mode to avoid dataloss and the ~30s delay bus reset
and renegotiation incurs.

Signed-off-by: Daniel J Blueman <daniel@quora.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/libata-core.c

@@ -4129,6 +4129,7 @@ static const struct ata_blacklist_entry ata_device_blacklist [] = {
 
 	/* Devices which aren't very happy with higher link speeds */
 	{ "WD My Book",			NULL,	ATA_HORKAGE_1_5_GBPS, },
+	{ "Seagate FreeAgent GoFlex",	NULL,	ATA_HORKAGE_1_5_GBPS, },
 
 	/*
 	 * Devices which choke on SETXFER.  Applies only if both the