video_osd: Add osd sandbox driver and tests

Add sandbox driver and tests for the new OSD uclass.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/video/sandbox_osd.h b/drivers/video/sandbox_osd.h
new file mode 100644
index 0000000..15a2c91
--- /dev/null
+++ b/drivers/video/sandbox_osd.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * (C) Copyright 2018
+ * Mario Six, Guntermann & Drunck GmbH, mario.six@gdsys.cc
+ */
+
+enum {
+	COLOR_BLACK,
+	COLOR_WHITE,
+	COLOR_RED,
+	COLOR_GREEN,
+	COLOR_BLUE,
+};