[VOL-3762] Updates to allow image download and update for the ONU

Change-Id: I0869307e3ef534c1d506b961d61a1ec6f5e13c2e
diff --git a/rw_core/mocks/adapter_onu.go b/rw_core/mocks/adapter_onu.go
index 361c7a1..fc24a3b 100644
--- a/rw_core/mocks/adapter_onu.go
+++ b/rw_core/mocks/adapter_onu.go
@@ -20,6 +20,7 @@
 	"context"
 	"errors"
 	"fmt"
+	"github.com/opencord/voltha-protos/v4/go/extension"
 	"strings"
 
 	"github.com/gogo/protobuf/proto"
@@ -127,6 +128,13 @@
 	return nil
 }
 
+// Single_get_value_request retrieves a single value.
+func (onuA *ONUAdapter) Single_get_value_request(ctx context.Context, // nolint
+	request extension.SingleGetValueRequest) (*extension.SingleGetValueResponse, error) {
+	logger.Fatalf(ctx, "Single_get_value_request unimplemented")
+	return nil, nil
+}
+
 // Disable_device disables device
 func (onuA *ONUAdapter) Disable_device(ctx context.Context, device *voltha.Device) error { // nolint
 	go func() {