ibmvnic: Validate napi exist before disabling them

Validate that the napi structs exist before trying to disable them
at driver close.
Signed-off-by: NNathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/ibm/ibmvnic.c

@@ -729,8 +729,10 @@ static int ibmvnic_close(struct net_device *netdev)
 	adapter->closing = true;
 	disable_sub_crqs(adapter);
 
+	if (adapter->napi) {
 		for (i = 0; i < adapter->req_rx_queues; i++)
 			napi_disable(&adapter->napi[i]);
+	}
 
 	if (!adapter->failover)
 		netif_tx_stop_all_queues(netdev);