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/imxrt1050-evk_defconfig b/configs/imxrt1050-evk_defconfig
index 9ab4d76..c12e04d 100644
--- a/configs/imxrt1050-evk_defconfig
+++ b/configs/imxrt1050-evk_defconfig
@@ -73,7 +73,7 @@
 CONFIG_USB=y
 # CONFIG_SPL_DM_USB is not set
 CONFIG_USB_EHCI_HCD=y
-CONFIG_DM_VIDEO=y
+CONFIG_VIDEO=y
 CONFIG_VIDEO_LOGO=y
 CONFIG_BACKLIGHT_GPIO=y
 CONFIG_SYS_WHITE_ON_BLACK=y