libnetwork/drivers/remote: remove unused testEndpoint.Interface

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

libnetwork/drivers/remote/driver_test.go

@@ -95,10 +95,6 @@ type testEndpoint struct {
 	disableGatewayService bool
 }
 
-func (test *testEndpoint) Interface() driverapi.InterfaceInfo {
-	return test
-}
-
 func (test *testEndpoint) Address() *net.IPNet {
 	if test.address == "" {
 		return nil