colibri-imx7: fix splash logo drawing

1. Configure white on black for video console.
2. Enable printing bmp logo during late board init stage.
3. Use iomux configuration from device tree.

Signed-off-by: Igor Opaniuk <igor.opaniuk@toradex.com>
diff --git a/configs/colibri_imx7_emmc_defconfig b/configs/colibri_imx7_emmc_defconfig
index 7538f7c..3056cc0 100644
--- a/configs/colibri_imx7_emmc_defconfig
+++ b/configs/colibri_imx7_emmc_defconfig
@@ -85,3 +85,5 @@
 CONFIG_DM_VIDEO=y
 CONFIG_FAT_WRITE=y
 CONFIG_OF_LIBFDT_OVERLAY=y
+CONFIG_BOARD_LATE_INIT=y
+CONFIG_SYS_WHITE_ON_BLACK=y