Manually revert incorrect change.

Change-Id: If8c21b26eb9c04ee640e3ba3a4ab170a5b5e4555

src/networks/model-net/fattree.c

@@ -1821,7 +1821,7 @@ void switch_buf_update_rc(switch_state * s,
         prepend_to_fattree_message_list(s->queued_msgs,
         s->queued_msgs_tail, indx, head);
         s->vc_occupancy[indx] -= s->params->chunk_size;
-        s->queued_length[indx] -= s->params->chunk_size;
+        s->queued_length[indx] += s->params->chunk_size;
     }
     if(bf->c2) 
     {
@@ -1855,7 +1855,7 @@ void switch_buf_update(switch_state * s, tw_bf * bf, fattree_message * msg,
     bf->c1 = 1;
     fattree_message_list *head = return_head( s->queued_msgs,
         s->queued_msgs_tail, indx);
-    s->queued_length[indx] += s->params->chunk_size;
+    s->queued_length[indx] -= s->params->chunk_size;
     switch_credit_send( s, bf,  &head->msg, lp, 1);
     append_to_fattree_message_list( s->pending_msgs, s->pending_msgs_tail,
       indx, head);