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/stemmy_defconfig b/configs/stemmy_defconfig
index f1d3ef5..90f2970 100644
--- a/configs/stemmy_defconfig
+++ b/configs/stemmy_defconfig
@@ -40,7 +40,7 @@
 CONFIG_USB_GADGET=y
 CONFIG_USB_GADGET_VENDOR_NUM=0x04e8
 CONFIG_USB_GADGET_PRODUCT_NUM=0x685d
-CONFIG_DM_VIDEO=y
+CONFIG_VIDEO=y
 CONFIG_SYS_WHITE_ON_BLACK=y
 CONFIG_VIDEO_MCDE_SIMPLE=y
 # CONFIG_EFI_LOADER is not set