route: Mark unused routing attributes as such

Also removes an unused policy entry for an attribute which is
only used in kernel->user direction.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index 44c81c7..a2aec2c 100644
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -267,10 +267,10 @@
 	RTA_PREFSRC,
 	RTA_METRICS,
 	RTA_MULTIPATH,
-	RTA_PROTOINFO,
+	RTA_PROTOINFO, /* no longer used */
 	RTA_FLOW,
 	RTA_CACHEINFO,
-	RTA_SESSION,
+	RTA_SESSION, /* no longer used */
 	RTA_MP_ALGO, /* no longer used */
 	RTA_TABLE,
 	__RTA_MAX