libata: initialize port_task when !CONFIG_ATA_SFF

ap->port_task was not initialized if !CONFIG_ATA_SFF later triggering
lockdep warning.  Make sure it's initialized.

Reported by Larry Finger.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 1ee9499..bbb3cae 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -5373,6 +5373,8 @@
 
 #ifdef CONFIG_ATA_SFF
 	INIT_DELAYED_WORK(&ap->port_task, ata_pio_task);
+#else
+	INIT_DELAYED_WORK(&ap->port_task, NULL);
 #endif
 	INIT_DELAYED_WORK(&ap->hotplug_task, ata_scsi_hotplug);
 	INIT_WORK(&ap->scsi_rescan_task, ata_scsi_dev_rescan);