input: move battery ADC call to timer call

src/input.h

@@ -0,0 +1,10 @@
+#pragma once
+
+#include "platform.h"
+
+void button_init(void);
+extern volatile int button_pressed[BUTTON_COUNT];
+
+int get_battery_percentage(void);
+int is_charging(void);
+int is_plugged(void);