libata passthru: support PIO multi commands

  support the pass through of PIO multi commands.

Signed-off-by: Albert Lee <albertcc@tw.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/include/linux/ata.h b/include/linux/ata.h
index edb31bf..3e95e5c 100644
--- a/include/linux/ata.h
+++ b/include/linux/ata.h
@@ -249,7 +249,7 @@
 	/* ATA taskfile protocols */
 	ATA_PROT_UNKNOWN,	/* unknown/invalid */
 	ATA_PROT_NODATA,	/* no data */
-	ATA_PROT_PIO,		/* PIO single sector */
+	ATA_PROT_PIO,		/* PIO data xfer */
 	ATA_PROT_DMA,		/* DMA */
 	ATA_PROT_NCQ,		/* NCQ */
 	ATA_PROT_ATAPI,		/* packet command, PIO data xfer*/