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/arch/Kconfig b/arch/Kconfig
index 1ffd77c..e3a456a 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -251,7 +251,7 @@
 	imply DM_SPI
 	imply DM_SPI_FLASH
 	imply DM_USB
-	imply DM_VIDEO
+	imply VIDEO
 	imply SYSRESET
 	imply SPL_SYSRESET
 	imply SYSRESET_X86