[SCSI] scsi_dh: Implement match callback function

Some device handler types are not tied to the vendor/model
but rather to a specific capability. Eg ALUA is supported
if the 'TPGS' setting in the standard inquiry is set.
This patch implements a 'match' callback for device handler
which supersedes the original vendor/model lookup and
implements the callback for the ALUA handler.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index f751d37..5591ed5 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -197,6 +197,7 @@
 	int (*activate)(struct scsi_device *, activate_complete, void *);
 	int (*prep_fn)(struct scsi_device *, struct request *);
 	int (*set_params)(struct scsi_device *, const char *);
+	bool (*match)(struct scsi_device *);
 };
 
 struct scsi_dh_data {