audio: Fixed condition to load AAC HW Encoder

- UseQCHWAACEncoder checks if the bitrate passed by the
  client is in the supported bit rate range of the
  AAC Hw Encoder. It is wrongly compared with the
  sample rate passed by the client instead of bitrate
  This is leading to loading of Hw Encoder even when
  unsupported bitrate is passed

- Fix is to correct the condition to compare with bitrate
  instead of sample rate

Change-Id: I88f4cbcf476dab8bd2bd44860b75ee3ffc3a5bb9
CRs-fixed: 659716