colibri-imx6ull: use splashcreen value instead of legacy function

Set proper splashscreen env value instead of calling legacy function
to show embed boot logo.

Fixes: 391c712dde("colibri-imx6ull: show boot logo")
Signed-off-by: Igor Opaniuk <igor.opaniuk@toradex.com>

board/toradex/colibri-imx6ull/colibri-imx6ull.c

@@ -173,8 +173,6 @@ int board_late_init(void)
 
 #if defined(CONFIG_DM_VIDEO)
 	setup_lcd();
-
-	show_boot_logo();
 #endif
 
 	return 0;