Correct the atoms.proto name

Test: run runtests.sh, make sure no missing test and get all pass
      run /out/host/linux-x86/bin/statsd_testdrive 103
      Got following metric data dump:pass for local test
Bug: 119862317

Change-Id: I4e003a0e392e15b71fb3ee3adf7de669ccf25d76