Convert CONFIG_VIDEO to Kconfig

This converts the following to Kconfig:
   CONFIG_VIDEO

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Jagan Teki <jteki@openedev.com>
diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index 86db0da..866fafd 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -434,4 +434,13 @@
 
 source "drivers/video/bridge/Kconfig"
 
+config VIDEO
+	bool "Enable legacy video support"
+	depends on !DM_VIDEO
+	help
+	  Define this for video support, without using driver model. Some
+	  drivers use this because they are not yet converted to driver
+	  model. Video drivers typically provide a colour text console and
+	  cursor.
+
 endmenu