Fix getIfNameListForLLOrIfname

The function is supposed to accept either a port logical label or
an interface name. Uplink probing refactoring broke this function and
it stopped recognizing interface name as the input argument.
This matters when device model contains port whose interface name and
logical label differ from each other.

Signed-off-by: Milan Lenco <milan@zededa.com>

pkg/pillar/cmd/zedrouter/networkinstance.go

@@ -1359,20 +1359,20 @@ func getIfNameListForLLOrIfname(
 	for _, port := range ports {
 		ifNameList = append(ifNameList, port.IfName)
 	}
+	if len(ifNameList) == 0 {
+		// llOrIfname is perhaps not a logical label but already an interface name.
+		if ctx.deviceNetworkStatus.GetPortByIfName(llOrIfname) != nil {
+			ifNameList = append(ifNameList, llOrIfname)
+		}
+	}
 	log.Functionf("ifNameList: %+v", ifNameList)
 
 	filteredList := make([]string, 0)
 	for _, ifName := range ifNameList {
 		// It is perfectly normal for DNS to list ports which do not actually
 		// exist (and have error reported).
-		dnsPort := ctx.deviceNetworkStatus.GetPortByIfName(ifName)
-		if dnsPort != nil {
-			if _, exists, _ := ctx.networkMonitor.GetInterfaceIndex(ifName); exists {
-				filteredList = append(filteredList, ifName)
-			}
-		} else {
-			log.Functionf("DeviceNetworkStatus not found for ifName(%s)",
-				ifName)
+		if _, exists, _ := ctx.networkMonitor.GetInterfaceIndex(ifName); exists {
+			filteredList = append(filteredList, ifName)
 		}
 	}
 	if len(filteredList) > 0 {