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/arm/Kconfig b/arch/arm/Kconfig
index 2e83394..6fb39e1 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1040,7 +1040,7 @@
 	select DM_SERIAL
 	select DM_SPI
 	select DM_USB
-	select DM_VIDEO
+	select VIDEO
 	select IOMMU
 	select LINUX_KERNEL_IMAGE_HEADER
 	select OF_BOARD_SETUP