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/rpi_4_defconfig b/configs/rpi_4_defconfig
index 1163750..46104c9 100644
--- a/configs/rpi_4_defconfig
+++ b/configs/rpi_4_defconfig
@@ -57,7 +57,7 @@
 CONFIG_USB_GADGET_PRODUCT_NUM=0xa4a5
 CONFIG_USB_GADGET_DWC2_OTG=y
 CONFIG_USB_GADGET_DOWNLOAD=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