ipvs: Use IS_ERR_OR_NULL(svc) instead of IS_ERR(svc) || svc == NULL

This minor refactoring does not change the logic of function
ip_vs_genl_dump_dests.

Signed-off-by: Gao Feng <fgao@ikuai8.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>

net/netfilter/ipvs/ip_vs_ctl.c

@@ -3260,7 +3260,7 @@ static int ip_vs_genl_dump_dests(struct sk_buff *skb,
 
 
 	svc = ip_vs_genl_find_service(ipvs, attrs[IPVS_CMD_ATTR_SERVICE]);
-	if (IS_ERR(svc) || svc == NULL)
+	if (IS_ERR_OR_NULL(svc))
 		goto out_err;
 
 	/* Dump the destinations */