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/blanktimer.hpp b/gui/blanktimer.hpp
index fe7b77c..6aca270 100644
--- a/gui/blanktimer.hpp
+++ b/gui/blanktimer.hpp
@@ -42,10 +42,11 @@
 
 	bool isScreenOff();
 
+	void blank(void);
+
 private:
 	void setTimer(void);
 	string getBrightness(void);
-	void blank(void);
 
 	pthread_mutex_t mutex;
 	enum State { kOn = 0, kDim = 1, kOff = 2, kBlanked = 3 };