VOL-1381 and VOL-1091 Add feature to collect PMmetrics of OLT, this will collect Tx and Rx and posts to kafka. This commit is also related to changes of commit 72b25abd4e804596413558ef10f098c2262dd65d voltha-go
Updated review comments

Updated with code optimization
Updated with dep files
Updated fix for sanity test
Updated with gomod changes

Change-Id: I899e855812a6eda812c64664a9154321cdb16876
diff --git a/vendor/github.com/opencord/voltha-lib-go/v2/pkg/pmmetrics/performance_metrics.go b/vendor/github.com/opencord/voltha-lib-go/v2/pkg/pmmetrics/performance_metrics.go
new file mode 100644
index 0000000..4bd0446
--- /dev/null
+++ b/vendor/github.com/opencord/voltha-lib-go/v2/pkg/pmmetrics/performance_metrics.go
@@ -0,0 +1,97 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+
+ * http://www.apache.org/licenses/LICENSE-2.0
+
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package pmmetrics
+
+import (
+	"github.com/opencord/voltha-protos/go/voltha"
+)
+
+// PmMetrics structure holds metric and device info
+type PmMetrics struct {
+	deviceID          string
+	frequency         uint32
+	grouped           bool
+	frequencyOverride bool
+	metrics           map[string]*voltha.PmConfig
+}
+
+type PmMetricsOption func(*PmMetrics)
+
+// Frequency is to poll stats at this interval
+func Frequency(frequency uint32) PmMetricsOption {
+	return func(args *PmMetrics) {
+		args.frequency = frequency
+	}
+}
+
+// GetSubscriberMetrics will return the metrics subscribed for the device.
+func (pm *PmMetrics) GetSubscriberMetrics() map[string]*voltha.PmConfig {
+	if pm == nil {
+		return nil
+	}
+	return pm.metrics
+}
+
+func Grouped(grouped bool) PmMetricsOption {
+	return func(args *PmMetrics) {
+		args.grouped = grouped
+	}
+}
+
+func FrequencyOverride(frequencyOverride bool) PmMetricsOption {
+	return func(args *PmMetrics) {
+		args.frequencyOverride = frequencyOverride
+	}
+}
+
+// Metrics will store the PMMetric params
+func Metrics(pmNames []string) PmMetricsOption {
+	return func(args *PmMetrics) {
+		args.metrics = make(map[string]*voltha.PmConfig)
+		for _, name := range pmNames {
+			args.metrics[name] = &voltha.PmConfig{
+				Name:    name,
+				Type:    voltha.PmConfig_COUNTER,
+				Enabled: true,
+			}
+		}
+	}
+}
+
+// NewPmMetrics will return the pmmetric object
+func NewPmMetrics(deviceID string, opts ...PmMetricsOption) *PmMetrics {
+	pm := &PmMetrics{}
+	pm.deviceID = deviceID
+	for _, option := range opts {
+		option(pm)
+	}
+	return pm
+}
+
+// ToPmConfigs will enable the defined pmmetric
+func (pm *PmMetrics) ToPmConfigs() *voltha.PmConfigs {
+	pmConfigs := &voltha.PmConfigs{
+		Id:           pm.deviceID,
+		DefaultFreq:  pm.frequency,
+		Grouped:      pm.grouped,
+		FreqOverride: pm.frequencyOverride,
+	}
+	for _, v := range pm.metrics {
+		pmConfigs.Metrics = append(pmConfigs.Metrics, &voltha.PmConfig{Name: v.Name, Type: v.Type, Enabled: v.Enabled})
+	}
+	return pmConfigs
+}