Checkmk Werk 8914: Fix calculation of latency for netapp_api_vs_traffic 2

ID: 8914 Title: Fix calculation of latency for netapp_api_vs_traffic 2 Component: Checks & agents Level: 1 Class: Bug fix Version: 1.7.0i1 read_ops and write_ops do not necessarily exist to use as reference for the avg_read_latency and avg_write_latency. The check now crashes when they are not available. This fix uses the latency and ops values in the isci and fcp namespaces and handles missing references. When the ref is missing, the time is taken as reference.