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/board/ge/mx53ppd/Makefile b/board/ge/mx53ppd/Makefile
index f423e80..9fae414 100644
--- a/board/ge/mx53ppd/Makefile
+++ b/board/ge/mx53ppd/Makefile
@@ -7,4 +7,4 @@
 # Jason Liu <r64343@freescale.com>
 
 obj-y			+= mx53ppd.o
-obj-$(CONFIG_DM_VIDEO)	+= mx53ppd_video.o
+obj-$(CONFIG_VIDEO)	+= mx53ppd_video.o