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
libstagefright: Fix to free buffers in error scenarios

- MediaBuffer objects are not freed if component transitions from
  IDLE->EXECUTING or EXECUTING->LOADED fails (or if the
  OMX_CmdComplete messages are dropped due to an earlier error)
  Additionally with native buffers, the corresponding
  ANativeWindowBuffers are not cancelled back in the above scenarios.

CRs-Fixed: 640236

Change-Id: I62bdcde5d52ee65cba457a9b5e938e0390d8d9b4