bootable: Change how blank screen works

This is required on some devices where previous to 8.1/8.0 the blank
screen flag worked but don't now.

Test: Tested on begonia, screen is now no longer black

Change-Id: Ib4ff607d220bcb1aa5166fea23cc7ecb0e012fdd
(cherry picked from commit 28d8dec40d60a31309fcf6259dad38cd328f0717)
diff --git a/gui/gui.cpp b/gui/gui.cpp
index 2a36fec..da35d23 100755
--- a/gui/gui.cpp
+++ b/gui/gui.cpp
@@ -755,6 +755,12 @@
 	gr_init();
 	TWFunc::Set_Brightness(DataManager::GetStrValue("tw_brightness"));
 
+#ifdef TW_SCREEN_BLANK_ON_BOOT
+        printf("TW_SCREEN_BLANK_ON_BOOT := true\n");
+        blankTimer.blank();
+        blankTimer.resetTimerAndUnblank();
+#endif
+
 	// load and show splash screen
 	if (PageManager::LoadPackage("splash", TWRES "splash.xml", "splash")) {
 		LOGERR("Failed to load splash screen XML.\n");