Windows: Fix volume_windows compile

Signed-off-by: John Howard <jhoward@microsoft.com>

daemon/volumes_windows.go

@@ -6,9 +6,9 @@ import "github.com/docker/docker/daemon/execdriver"
 
 // Not supported on Windows
 func copyOwnership(source, destination string) error {
-	return nil, nil
+	return nil
 }
 
 func (container *Container) setupMounts() ([]execdriver.Mount, error) {
-	return nil
+	return nil, nil
 }