Add backend support for bandwidth control

httpd/page_impl.h

@@ -5,6 +5,7 @@ void send_counters(char port);
 void send_status(void);
 void send_vlan(uint16_t vlan);
 void send_basic_info(void);
+void send_bandwidth(void);
 void send_eee(void);
 void send_l2(uint16_t idx);
 void l2_delete(uint16_t idx);