project: enable battery voltage checking

Enable battery voltage checking before flashing or erasing
image.

Change-Id: Ie95f3b88d20b19cea711f9cef980590ceed0ff89
diff --git a/project/msm8916.mk b/project/msm8916.mk
index 0edff28..2ac68fb 100644
--- a/project/msm8916.mk
+++ b/project/msm8916.mk
@@ -60,3 +60,6 @@
 ENABLE_REBOOT_MODULE := 1
 #Use PON register for reboot reason
 DEFINES += USE_PON_REBOOT_REG=1
+
+#enable battery voltage check
+DEFINES += CHECK_BAT_VOLTAGE=1