Add ro.pa property, used by ParanoidOTA

Patch Set 2:
Move the property to pa_overrides.mk

Change-Id: I8e59ab044a4fc1bda9b35a13bdc3a722b3a23dc3
Merge "Add ro.pa property, used by ParanoidOTA" into kitkat
OTA system(vendor part)

Change-Id: I0c48e142fb0bdad72cbeaa021289758802f141e2