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/configs/libretech-s912-pc_defconfig b/configs/libretech-s912-pc_defconfig
index 7819e72..63137eb5 100644
--- a/configs/libretech-s912-pc_defconfig
+++ b/configs/libretech-s912-pc_defconfig
@@ -71,7 +71,7 @@
 CONFIG_USB_GADGET_PRODUCT_NUM=0xfada
 CONFIG_USB_GADGET_DWC2_OTG=y
 CONFIG_USB_GADGET_DOWNLOAD=y
-CONFIG_DM_VIDEO=y
+CONFIG_VIDEO=y
 CONFIG_SYS_WHITE_ON_BLACK=y
 CONFIG_VIDEO_MESON=y
 CONFIG_VIDEO_DT_SIMPLEFB=y