video: Rename CONFIG_DM_VIDEO to CONFIG_VIDEO

Now that all the old code is gone, rename this option. Driver model
migration is now complete.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/configs/meson64.h b/include/configs/meson64.h
index 40803ee..0c41df2 100644
--- a/include/configs/meson64.h
+++ b/include/configs/meson64.h
@@ -17,7 +17,7 @@
 #endif
 
 /* For splashscreen */
-#ifdef CONFIG_DM_VIDEO
+#ifdef CONFIG_VIDEO
 #define STDOUT_CFG "vidconsole,serial"
 #else
 #define STDOUT_CFG "serial"