video: Convert CONFIG_VIDEO_LOGO to Kconfig

This converts the following to Kconfig:
   CONFIG_VIDEO_LOGO

Note that this option depends on CONFIG_DM_VIDEO now, since cfb_console is
deprecated. The only relevant code is now in splash.c

Drop the check for DM_VIDEO in that file.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index a58f87f..7a73ecc 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -14,6 +14,15 @@
 	  option compiles in the video uclass and routes all LCD/video access
 	  through this.
 
+config VIDEO_LOGO
+	bool "Show the U-Boot logo on the display"
+	depends on DM_VIDEO
+	help
+	  This enables showing the U-Boot logo on the display when a video
+	  device is probed. It appears at the top right. The logo itself is at
+	  tools/logos/u-boot_logo.bmp and looks best when the display has a
+	  black background.
+
 config BACKLIGHT
 	bool "Enable panel backlight uclass support"
 	depends on DM_VIDEO