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/configs/sandbox_flattree_defconfig b/configs/sandbox_flattree_defconfig
index 618d646..3dcfdcc 100644
--- a/configs/sandbox_flattree_defconfig
+++ b/configs/sandbox_flattree_defconfig
@@ -31,6 +31,7 @@
 CONFIG_CMD_GPIO=y
 CONFIG_CMD_GPT=y
 CONFIG_CMD_I2C=y
+CONFIG_CMD_OSD=y
 CONFIG_CMD_PCI=y
 CONFIG_CMD_REMOTEPROC=y
 CONFIG_CMD_SF=y
@@ -167,6 +168,8 @@
 CONFIG_CONSOLE_TRUETYPE=y
 CONFIG_CONSOLE_TRUETYPE_CANTORAONE=y
 CONFIG_VIDEO_SANDBOX_SDL=y
+CONFIG_OSD=y
+CONFIG_SANDBOX_OSD=y
 CONFIG_CMD_DHRYSTONE=y
 CONFIG_TPM=y
 CONFIG_LZ4=y