Fixup linting issues

* Disbale unused-parameter check.
* Fixup minor linting issues.

Signed-off-by: Ben Kochie <superq@gmail.com>

.golangci.yml

@@ -25,3 +25,9 @@ linters-settings:
       - (net/http.ResponseWriter).Write
       # Never check for logger errors.
       - (github.com/go-kit/log.Logger).Log
+  revive:
+    rules:
+      # https://github.com/mgechev/revive/blob/master/RULES_DESCRIPTIONS.md#unused-parameter
+      - name: unused-parameter
+        severity: warning
+        disabled: true

collector/ipvs_linux_test.go

@@ -209,9 +209,8 @@ func TestIPVSCollectorResponse(t *testing.T) {
 					if want == got {
 						// this is a line we are interested in, and it is correct
 						continue wantLoop
-					} else {
-						gotLinesIdx++
 					}
+					gotLinesIdx++
 				}
 				// if this point is reached, the line we want was missing
 				t.Fatalf("Missing expected output line(s), first missing line is %s", want)

collector/perf_linux_test.go

@@ -54,7 +54,9 @@ func TestPerfCollector(t *testing.T) {
 	metrics := make(chan prometheus.Metric)
 	defer close(metrics)
 	go func() {
+		i := 0
 		for range metrics {
+			i++
 		}
 	}()
 	if err := collector.Update(metrics); err != nil {

collector/systemd_linux.go

@@ -334,9 +334,7 @@ func (c *systemdCollector) collectSockets(conn *dbus.Conn, ch chan<- prometheus.
 
 		// NRefused wasn't added until systemd 239.
 		refusedConnectionCount, err := conn.GetUnitTypePropertyContext(context.TODO(), unit.Name, "Socket", "NRefused")
-		if err != nil {
-			//log.Debugf("couldn't get unit '%s' NRefused: %s", unit.Name, err)
-		} else {
+		if err == nil {
 			ch <- prometheus.MustNewConstMetric(
 				c.socketRefusedConnectionsDesc, prometheus.GaugeValue,
 				float64(refusedConnectionCount.Value.Value().(uint32)), unit.Name)