main: Add empty battery screen

This disables low battery monitor shutdown (LBM shutdown) on boot and checks if battery is enough.

The logic is as follows:

If battery is not enough:
- If not charging and 15s pass, it will re enable LBM shutdown and power off.
- If charging, it will wait until it is charged above the limit.
 Screen will auto turn off to save power. A press on Power button or a change on charger, will enable it for another 15s.

If battery is enough:
- Enables LBM shutdown and continues with the boot process.

bootloader/power/max7762x.c

@@ -169,9 +169,9 @@ void max77620_config_default()
 	_max77620_try_set_reg(MAX77620_REG_SD_CFG2, 4);
 }
 
-void max77620_low_battery_monitor_config()
+void max77620_low_battery_monitor_config(bool enable)
 {
 	_max77620_try_set_reg(MAX77620_REG_CNFGGLBL1,
-		MAX77620_CNFGGLBL1_LBDAC_EN | MAX77620_CNFGGLBL1_MPPLD |
+		MAX77620_CNFGGLBL1_LBDAC_EN | (enable ? MAX77620_CNFGGLBL1_MPPLD : 0) |
 		MAX77620_CNFGGLBL1_LBHYST_200 | MAX77620_CNFGGLBL1_LBDAC_2800);
 }

bootloader/power/max7762x.h

@@ -113,6 +113,6 @@ int max77620_regulator_set_voltage(u32 id, u32 mv);
 int max77620_regulator_enable(u32 id, int enable);
 int max77620_regulator_set_volt_and_flags(u32 id, u32 mv, u8 flags);
 void max77620_config_default();
-void max77620_low_battery_monitor_config();
+void max77620_low_battery_monitor_config(bool enable);
 
 #endif