* Rename hals.conf -> _hals.conf so legitimate
MultiHAL won't attempt to load our HALs.
* Rename multihal -> multihal-samsung8974 so soong
doesn't complain about duplicate package names.
* Remove USE_SENSOR_MULTI_HAL flag requirement so
we can actually build it.
* Use TARGET_BOARD_PLATFORM variable in package
name because it's a common tree.
Change-Id: Ifa8c20747e3f0bf9bae8b42dd4c499cf6d770e27
