[SCSI] libsas: convert dev->gone to flags

In preparation for adding tracking of another device state "destroy".

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

include/scsi/libsas.h

@@ -173,7 +173,10 @@ struct sata_device {
 	struct ata_taskfile tf;
 };
 
-/* ---------- Domain device ---------- */
+enum {
+	SAS_DEV_GONE,
+};
+
 struct domain_device {
         enum sas_dev_type dev_type;
 
@@ -205,7 +208,7 @@ struct domain_device {
         };
 
         void *lldd_dev;
-	int gone;
+	unsigned long state;
 	struct kref kref;
 };