[VOL-2972] Revert added flows on failure

This commit consists of:
1) Reverts added flows on flow addition failure (e.g. one adapter
may return a failure in which case any corresponding flow that
has been successfully added to the other adapter will be removed).
The corresponding logical device flow will be removed as well.

2) Some minor refactoring in the mocks adapter

3) Some minor logging change to decrease the clutter when running
unit tests.

Change-Id: Ia63243e83516ef81152893563bef76c830bea022
diff --git a/rw_core/mocks/adapter_onu.go b/rw_core/mocks/adapter_onu.go
index 5f4a5e6..217f01d 100644
--- a/rw_core/mocks/adapter_onu.go
+++ b/rw_core/mocks/adapter_onu.go
@@ -20,9 +20,6 @@
 	"context"
 	"errors"
 	"fmt"
-	"strings"
-	"sync"
-
 	"github.com/gogo/protobuf/proto"
 	"github.com/opencord/voltha-lib-go/v3/pkg/adapters/adapterif"
 	com "github.com/opencord/voltha-lib-go/v3/pkg/adapters/common"
@@ -30,22 +27,18 @@
 	ic "github.com/opencord/voltha-protos/v3/go/inter_container"
 	of "github.com/opencord/voltha-protos/v3/go/openflow_13"
 	"github.com/opencord/voltha-protos/v3/go/voltha"
+	"strings"
 )
 
 // ONUAdapter represent ONU adapter attributes
 type ONUAdapter struct {
-	flows map[uint64]*voltha.OfpFlowStats
-	lock  sync.Mutex
-	Adapter
+	*Adapter
 }
 
 // NewONUAdapter creates ONU adapter
 func NewONUAdapter(cp adapterif.CoreProxy) *ONUAdapter {
 	return &ONUAdapter{
-		flows: map[uint64]*voltha.OfpFlowStats{},
-		Adapter: Adapter{
-			coreProxy: cp,
-		},
+		Adapter: NewAdapter(cp),
 	}
 }
 
@@ -116,9 +109,7 @@
 			logger.Fatalf("getting-device-failed-%s", err)
 		}
 
-		if err = onuA.updateDevice(d); err != nil {
-			logger.Fatalf("saving-device-failed-%s", err)
-		}
+		onuA.updateDevice(d)
 	}()
 	return nil
 }
@@ -168,9 +159,7 @@
 			logger.Warnw("device-state-update-failed", log.Fields{"deviceId": device.Id, "error": err})
 			return
 		}
-		if err := onuA.updateDevice(cloned); err != nil {
-			logger.Fatalf("saving-device-failed-%s", err)
-		}
+		onuA.updateDevice(cloned)
 	}()
 	return nil
 }
@@ -195,53 +184,18 @@
 		if err := onuA.coreProxy.DeviceStateUpdate(context.TODO(), cloned.Id, cloned.ConnectStatus, cloned.OperStatus); err != nil {
 			logger.Fatalf("device-state-update-failed", log.Fields{"deviceId": device.Id, "error": err})
 		}
-		if err := onuA.updateDevice(cloned); err != nil {
-			logger.Fatalf("saving-device-failed-%s", err)
-		}
+
+		onuA.updateDevice(cloned)
 	}()
 	return nil
 }
 
-// Update_flows_incrementally mocks the incremental flow update
-func (onuA *ONUAdapter) Update_flows_incrementally(device *voltha.Device, flows *of.FlowChanges, groups *of.FlowGroupChanges, flowMetadata *voltha.FlowMetadata) error { // nolint
-	onuA.lock.Lock()
-	defer onuA.lock.Unlock()
-
-	if flows.ToAdd != nil {
-		for _, f := range flows.ToAdd.Items {
-			onuA.flows[f.Id] = f
-		}
-	}
-	if flows.ToRemove != nil {
-		for _, f := range flows.ToRemove.Items {
-			delete(onuA.flows, f.Id)
-		}
-	}
-	return nil
-}
-
 // Start_omci_test begins an omci self-test
 func (onuA *ONUAdapter) Start_omci_test(device *voltha.Device, request *voltha.OmciTestRequest) (*ic.TestResponse, error) { // nolint
 	_ = device
 	return &ic.TestResponse{Result: ic.TestResponse_SUCCESS}, nil
 }
 
-// GetFlowCount returns the total number of flows presently under this adapter
-func (onuA *ONUAdapter) GetFlowCount() int {
-	onuA.lock.Lock()
-	defer onuA.lock.Unlock()
-
-	return len(onuA.flows)
-}
-
-// ClearFlows removes all flows in this adapter
-func (onuA *ONUAdapter) ClearFlows() {
-	onuA.lock.Lock()
-	defer onuA.lock.Unlock()
-
-	onuA.flows = map[uint64]*voltha.OfpFlowStats{}
-}
-
 func (onuA *ONUAdapter) Get_ext_value(deviceId string, device *voltha.Device, valueflag voltha.ValueType_Type) (*voltha.ReturnValues, error) { // nolint
 	_ = deviceId
 	_ = device