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/configs/cm_fx6_defconfig b/configs/cm_fx6_defconfig
index b823a15..4e7f152 100644
--- a/configs/cm_fx6_defconfig
+++ b/configs/cm_fx6_defconfig
@@ -106,6 +106,7 @@
 CONFIG_USB_KEYBOARD=y
 CONFIG_SYS_USB_EVENT_POLL_VIA_INT_QUEUE=y
 CONFIG_DM_VIDEO=y
+CONFIG_VIDEO_LOGO=y
 CONFIG_VIDEO_IPUV3=y
 CONFIG_SPLASH_SCREEN=y
 CONFIG_SPLASH_SOURCE=y