[SCSI] libsas: make ATA functions selectable by a config option

Not everyone wants libsas automatically to pull in libata.  This patch
makes the behaviour configurable, so you can build libsas with or
without ATA support.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

include/scsi/sas_ata.h

diff --git a/include/scsi/sas_ata.h b/include/scsi/sas_ata.h
index 3407c81..dd5edc9 100644
--- a/include/scsi/sas_ata.h
+++ b/include/scsi/sas_ata.h
@@ -28,6 +28,8 @@
 #include <linux/libata.h>
 #include <scsi/libsas.h>
 
+#ifdef CONFIG_SCSI_SAS_ATA
+
 static inline int dev_is_sata(struct domain_device *dev)
 {
 	return (dev->rphy->identify.target_port_protocols & SAS_PROTOCOL_SATA);
@@ -38,4 +40,21 @@
 
 void sas_ata_task_abort(struct sas_task *task);
 
+#else
+
+
+static inline int dev_is_sata(struct domain_device *dev)
+{
+	return 0;
+}
+int sas_ata_init_host_and_port(struct domain_device *found_dev,
+			       struct scsi_target *starget)
+{
+	return 0;
+}
+void sas_ata_task_abort(struct sas_task *task)
+{
+}
+#endif
+
 #endif /* _SAS_ATA_H_ */