sched: remove unused backlog in RED stats

The RED statistics structure includes backlog field which is not
set or used by any code.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/red.h

@@ -97,7 +97,6 @@ struct red_stats {
 	u32		forced_mark;	/* Forced marks, qavg > max_thresh */
 	u32		pdrop;          /* Drops due to queue limits */
 	u32		other;          /* Drops due to drop() calls */
-	u32		backlog;
 };
 
 struct red_parms {