net: skb: change the definition SKB_DR_SET()

The SKB_DR_OR() is used to set the drop reason to a value when it is
not set or specified yet. SKB_NOT_DROPPED_YET should also be considered
as not set.
Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/skbuff.h

@@ -510,7 +510,8 @@ enum skb_drop_reason {
 	(name = SKB_DROP_REASON_##reason)
 #define SKB_DR_OR(name, reason)					\
 	do {							\
-		if (name == SKB_DROP_REASON_NOT_SPECIFIED)	\
+		if (name == SKB_DROP_REASON_NOT_SPECIFIED ||	\
+		    name == SKB_NOT_DROPPED_YET)		\
 			SKB_DR_SET(name, reason);		\
 	} while (0)