mvpp2: fix netmap_stop procedure

When disabling netmap the stop procedure would not function correctly
for mvpp2 CP units with more than 1 port in use.

Change pool/memory free condition such that it only occurs once per CP
unit. Also change the rx offset change to use the rxq id (similar change
to netmap_start procedure).

LINUX/mvpp2_netmap.h

@@ -506,18 +506,19 @@ static void mvpp2_netmap_stop(struct netmap_adapter *na)
 
 	/* Use native BM pools for this port */
 	for (i = 0; i < port->nrxqs; i++) {
-		mvpp2_rxq_drop_pkts(port, port->rxqs[i]);
+		struct mvpp2_rx_queue *rxq = port->rxqs[i];
+		mvpp2_rxq_drop_pkts(port, rxq);
 		mvpp2_rxq_short_pool_set(port, i, 0); /* MVPP2_BM_SHORT */
 		mvpp2_rxq_long_pool_set(port, i, 1); /* MVPP2_BM_LONG */
-		mvpp2_rxq_offset_set(port, i, MVPP2_SKB_HEADROOM);
+		mvpp2_rxq_offset_set(port, rxq->id, MVPP2_SKB_HEADROOM);
 	}
 
 	/* Re-enable ingress if interface was running */
 	if (running)
 		mvpp2_ingress_enable(port);
 
 	/* Free all netmap buffers and pools if no longer needed */
-	if (mvpp2_netmap_users(priv) <= 1) {
+	if (mvpp2_netmap_users(priv) == 0) {
 		mvpp2_netmap_destroy_pools (na);
 	}