colibri imx6/t20: enable CONFIG_SYS_WHITE_ON_BLACK

Enable CONFIG_SYS_WHITE_ON_BLACK by default for DM_VIDEO enabled
configurations, where env("splashimage") is used for showing Toradex
boot logo.

Signed-off-by: Igor Opaniuk <igor.opaniuk@toradex.com>
diff --git a/configs/colibri_imx6_defconfig b/configs/colibri_imx6_defconfig
index 72e9128..9e307da 100644
--- a/configs/colibri_imx6_defconfig
+++ b/configs/colibri_imx6_defconfig
@@ -85,3 +85,4 @@
 CONFIG_VIDEO_IPUV3=y
 CONFIG_FAT_WRITE=y
 CONFIG_OF_LIBFDT_OVERLAY=y
+CONFIG_SYS_WHITE_ON_BLACK=y
diff --git a/configs/colibri_t20_defconfig b/configs/colibri_t20_defconfig
index 15fb955..d1bfd3c 100644
--- a/configs/colibri_t20_defconfig
+++ b/configs/colibri_t20_defconfig
@@ -64,3 +64,4 @@
 CONFIG_VIDEO_TEGRA20=y
 CONFIG_CONSOLE_SCROLL_LINES=10
 CONFIG_OF_LIBFDT_OVERLAY=y
+CONFIG_SYS_WHITE_ON_BLACK=y