[SCSI] libsas: disable scanning lun > 0 on ata devices

Currently mvsas and pm8001 have custom ->slave_alloc implementations to
achieve this.  Uplevel it for all libsas drivers as isci encounters problems
with atapi devices when scanning past lun0.

Just do what Darrick suggested [1], and limit the scan for ata devices.

[1] http://marc.info/?l=linux-scsi&m=116604101119861&w=2

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/scsi_transport_sas.c

@@ -1545,8 +1545,14 @@ int sas_rphy_add(struct sas_rphy *rphy)
 
 	if (identify->device_type == SAS_END_DEVICE &&
 	    rphy->scsi_target_id != -1) {
-		scsi_scan_target(&rphy->dev, 0,
-				rphy->scsi_target_id, SCAN_WILD_CARD, 0);
+		int lun;
+
+		if (identify->target_port_protocols & SAS_PROTOCOL_SSP)
+			lun = SCAN_WILD_CARD;
+		else
+			lun = 0;
+
+		scsi_scan_target(&rphy->dev, 0, rphy->scsi_target_id, lun, 0);
 	}
 
 	return 0;