[SCSI] correct some dropped const compiler warnings

Make the vendor, model and rev fields in scsi_device pointers to const
and update a few prototypes of functions using them.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h
index d632d9e..a8d121c 100644
--- a/drivers/scsi/scsi_priv.h
+++ b/drivers/scsi/scsi_priv.h
@@ -57,7 +57,8 @@
 
 /* scsi_devinfo.c */
 extern int scsi_get_device_flags(struct scsi_device *sdev,
-				 unsigned char *vendor, unsigned char *model);
+				 const unsigned char *vendor,
+				 const unsigned char *model);
 extern int __init scsi_init_devinfo(void);
 extern void scsi_exit_devinfo(void);