statsd_drm: skip empty pulled atoms

Bug: 184263266
Test: Local Testing of New Atoms/Metrics
Test: http://doc/1pY7g5Xl0_aZ8JC6chQWUg9LHeBsjf2rNtqdc62IMIo8
Change-Id: I789cf3fba8d1ce3ee7477026ee3bd5d57d70b601
2 files changed