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/khadas-vim3_android_defconfig b/configs/khadas-vim3_android_defconfig
index f076b6e..827e994 100644
--- a/configs/khadas-vim3_android_defconfig
+++ b/configs/khadas-vim3_android_defconfig
@@ -93,7 +93,7 @@
 CONFIG_USB_GADGET_PRODUCT_NUM=0xfada
 CONFIG_USB_GADGET_DWC2_OTG=y
 CONFIG_USB_GADGET_DWC2_OTG_PHY_BUS_WIDTH_8=y
-CONFIG_DM_VIDEO=y
+CONFIG_VIDEO=y
 # CONFIG_VIDEO_BPP8 is not set
 # CONFIG_VIDEO_BPP16 is not set
 CONFIG_SYS_WHITE_ON_BLACK=y