AudioService: initialize sensors if head tracking supported

Query ISpatializer to check if head tracking is supported to
determine whether to initialize sensors

Bug: 202515176
Test: after boot on device with head tracking, grep logcat for
SpatializerHelper, verify no "not initializing sensors" message
Change-Id: I02de212452c7beaa8c06776c34eb6005da0e9073

Change-Id: I5050a4507c9c84a9fa166943f28b3cd92b789419