libata: rename SFF port ops

Add sff_ prefix to SFF specific port ops.

This rename is in preparation of separating SFF support out of libata
core layer.  This patch strictly renames ops and doesn't introduce any
behavior difference.

Signed-off-by: Tejun Heo <htejun@gmail.com>
diff --git a/drivers/ata/pata_mpc52xx.c b/drivers/ata/pata_mpc52xx.c
index 5d1d32a..bc79df6 100644
--- a/drivers/ata/pata_mpc52xx.c
+++ b/drivers/ata/pata_mpc52xx.c
@@ -261,7 +261,7 @@
 
 static struct ata_port_operations mpc52xx_ata_port_ops = {
 	.inherits		= &ata_sff_port_ops,
-	.dev_select		= mpc52xx_ata_dev_select,
+	.sff_dev_select		= mpc52xx_ata_dev_select,
 	.cable_detect		= ata_cable_40wire,
 	.set_piomode		= mpc52xx_ata_set_piomode,
 	.post_internal_cmd	= ATA_OP_NULL,