openvswitch: correct an invalid BUG_ON

table->count is uint32_t
Signed-off-by: Hong Zhiguo <honkiko@gmail.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>

net/openvswitch/flow.c

@@ -795,9 +795,9 @@ void ovs_flow_tbl_insert(struct flow_table *table, struct sw_flow *flow)
 
 void ovs_flow_tbl_remove(struct flow_table *table, struct sw_flow *flow)
 {
+	BUG_ON(table->count == 0);
 	hlist_del_rcu(&flow->hash_node[table->node_ver]);
 	table->count--;
-	BUG_ON(table->count < 0);
 }
 
 /* The size of the argument for each %OVS_KEY_ATTR_* Netlink attribute.  */