Merge changes Ic378d0e5,Ib3a8696a

* changes:
  remove unused enum value BpfLevel::NONE
  remove unused function BpfLevelToString()
tree: 8856b2e40654686083ae50dddc87e27e3f4edbfa
  1. bpfloader/
  2. libbpf_android/
  3. progs/
  4. Android.bp
  5. NOTICE
  6. OWNERS
  7. PREUPLOAD.cfg