Starting from GB, modules which doesn't have LOCAL_MODULE_TAGS defined (default to user tag) or which has user tag and not part of GRANDFATHERED_USER_MODULES does throgh ERROR/WARNING message. To supress these WARNING messages, we need to add optional tag. Targets tested on: msm8660_surf Tests: Did a build from scratch Change-Id: I006ae23366cf1f517f0c68f66f607be1455b4ba9