Audio: Enable QCOM HW AAC encoder

- Check related system prop to enable QCOM's HW
  AAC encoder
- Use QCOM's HW AAC encoder only for supported
  channels/sample rate/bitrate.
- Use Google's SW AAC encoder if the required AAC
  audio parameter is not supported by QCOM's HW
  AAC encoder
- Extend utils for more generic support

Change-Id: Ib1097611b1dbf59a7cf846aa7f944f604ad8a622