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/seaboard_defconfig b/configs/seaboard_defconfig
index e3895f5..2b96ec5 100644
--- a/configs/seaboard_defconfig
+++ b/configs/seaboard_defconfig
@@ -60,7 +60,7 @@
 CONFIG_USB_KEYBOARD=y
 CONFIG_USB_HOST_ETHER=y
 CONFIG_USB_ETHER_ASIX=y
-CONFIG_DM_VIDEO=y
+CONFIG_VIDEO=y
 # CONFIG_VIDEO_BPP8 is not set
 CONFIG_VIDEO_TEGRA20=y
 CONFIG_CONSOLE_SCROLL_LINES=10