SensorManager fixes.

i) Use pingBinder() to check the status of sensorservice everytime an
   event_queue is created. Retry to establish the binder connection if
   SensorService has recovered from a runtime restart.
ii) LOG_ALWAYS_FATAL_IF getService(SensorService) returns NULL or malloc
    returns NULL.

Bug: 22634472
Change-Id: I4e3912839b6f4114be1a124510878774dbd576a4