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/common/board_f.c b/common/board_f.c
index 0f7354d..51ba593 100644
--- a/common/board_f.c
+++ b/common/board_f.c
@@ -408,7 +408,7 @@
 
 static int reserve_video(void)
 {
-	if (IS_ENABLED(CONFIG_DM_VIDEO)) {
+	if (IS_ENABLED(CONFIG_VIDEO)) {
 		ulong addr;
 		int ret;