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/mach-imx/mx7/soc.c b/arch/arm/mach-imx/mx7/soc.c
index c672be5..02af0d5 100644
--- a/arch/arm/mach-imx/mx7/soc.c
+++ b/arch/arm/mach-imx/mx7/soc.c
@@ -447,7 +447,7 @@
 void reset_misc(void)
 {
 #ifndef CONFIG_SPL_BUILD
-#if defined(CONFIG_VIDEO_MXS) && !defined(CONFIG_DM_VIDEO)
+#if defined(CONFIG_VIDEO_MXS) && !defined(CONFIG_VIDEO)
 	lcdif_power_down();
 #endif
 #endif