[host] app: zero the new client sub count

If a new client connects but there has not been a capture timeout the
new client count wont be zeroed on a valid capture. If there is a
timeout later the host will still think there is a new client and
re-send a frame when it should not. This fixes this by reading the value
on a valid frame which zeros the new subs count.

host/src/app.c

@@ -185,6 +185,8 @@ static bool sendFrame(void)
   switch(app.iface->waitFrame(&frame, app.maxFrameSize))
   {
     case CAPTURE_RESULT_OK:
+      // reading the new subs count zeros it
+      lgmpHostQueueNewSubs(app.frameQueue);
       break;
 
     case CAPTURE_RESULT_REINIT: