target: add api to get battery info

Add api to get battery's voltage and add safeguards such as
refusing to flash if minimum battery levels are not present or
be bypass if the device doesn't have a battery

Change-Id: Ie9fc45cd2d3a5f588acedef4fd9b0ffdcb2eae24
diff --git a/include/target.h b/include/target.h
index f2e2acd..6f83b6f 100644
--- a/include/target.h
+++ b/include/target.h
@@ -92,4 +92,8 @@
 uint32_t get_vibration_type();
 #endif
 
+uint32_t target_get_battery_voltage();
+bool target_battery_soc_ok();
+bool target_battery_is_present();
+uint32_t target_get_pmic();
 #endif