secchan: Fix port status detection

secchan was reporting the *opposite* port status for port down/link
down.

Bug reported by: Takayuki Hama <t-hama@cb.jp.nec.com>

secchan/port-watcher.c

@@ -384,8 +384,8 @@ port_watcher_periodic_cb(void *pw_)
         }
 
         new_opp = *opp;
-        set_bit(htonl(OFPPC_PORT_DOWN), flags & NETDEV_UP, &new_opp.config);
-        set_bit(htonl(OFPPS_LINK_DOWN), flags & NETDEV_CARRIER,
+        set_bit(htonl(OFPPC_PORT_DOWN), ~flags & NETDEV_UP, &new_opp.config);
+        set_bit(htonl(OFPPS_LINK_DOWN), ~flags & NETDEV_CARRIER,
                 &new_opp.state);
         if (opp->config != new_opp.config || opp->state != new_opp.state) {
             struct ofp_port_status *ops;