Fix various issues with bluetooth SCO

- Changes in input and output sampling rate must be synchronized with
reads and writes respectively.
- Both input and output sampling rates must be changed simultaneously to 8k
when bluetooth device is selected for either input or output. The I2S connection
to BT chip must also be switched while both input and output DMAs are stopped.
- Fixed a bug with resampler buffer initialization

Change-Id: I77226817c04d2401b28d9d3bc4f0d2d14897fa51
2 files changed