libata bugfix: preserve LBA bit for HDIO_DRIVE_TASK

Preserve the LBA bit in the DevSel/Head register for HDIO_DRIVE_TASK.

Signed-off-by:  Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 6cc817a..e936443 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -333,7 +333,7 @@
 	scsi_cmd[8]  = args[3];
 	scsi_cmd[10] = args[4];
 	scsi_cmd[12] = args[5];
-	scsi_cmd[13] = args[6] & 0x0f;
+	scsi_cmd[13] = args[6] & 0x4f;
 	scsi_cmd[14] = args[0];
 
 	/* Good values for timeout and retries?  Values below