target: project: msm8916: Add macro for PON register

Add macro enable usage of PON register for reboot reason, remove
shutdown_device api from target code and add pmic reset api for this
target

Change-Id: I5b7e119d8c41f57da1b15e40cf47289be854bc34
diff --git a/project/msm8916.mk b/project/msm8916.mk
index 5891664..0edff28 100644
--- a/project/msm8916.mk
+++ b/project/msm8916.mk
@@ -58,3 +58,5 @@
 
 #Enable the external reboot functions
 ENABLE_REBOOT_MODULE := 1
+#Use PON register for reboot reason
+DEFINES += USE_PON_REBOOT_REG=1