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/rpi_0_w_defconfig b/configs/rpi_0_w_defconfig
index 0bac245..6766451 100644
--- a/configs/rpi_0_w_defconfig
+++ b/configs/rpi_0_w_defconfig
@@ -41,7 +41,7 @@
 CONFIG_USB_KEYBOARD=y
 CONFIG_USB_HOST_ETHER=y
 CONFIG_USB_ETHER_SMSC95XX=y
-CONFIG_DM_VIDEO=y
+CONFIG_VIDEO=y
 # CONFIG_VIDEO_BPP8 is not set
 # CONFIG_VIDEO_BPP16 is not set
 CONFIG_SYS_WHITE_ON_BLACK=y