[PATCH] libata: implement ata_dev_enabled and disabled()

This patch renames ata_dev_present() to ata_dev_enabled() and adds
ata_dev_disabled().  This is to discern the state where a device is
present but disabled from not-present state.  This disctinction is
necessary when configuring transfer mode because device selection
timing must not be violated even if a device fails to configure.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/scsi/sata_sil.c b/drivers/scsi/sata_sil.c
index 18c296c..d6c7086 100644
--- a/drivers/scsi/sata_sil.c
+++ b/drivers/scsi/sata_sil.c
@@ -264,7 +264,7 @@
 
 	for (i = 0; i < 2; i++) {
 		dev = &ap->device[i];
-		if (!ata_dev_present(dev))
+		if (!ata_dev_enabled(dev))
 			dev_mode[i] = 0;	/* PIO0/1/2 */
 		else if (dev->flags & ATA_DFLAG_PIO)
 			dev_mode[i] = 1;	/* PIO3/4 */