remote_submix: Fix resampler and channel conversion

* Add support for multiple channels to resampler
* Fix out-of-bounds write during channel conversion.
  When pipe stream is stereo and input stream is mono, it will do
  inplace conversion. But the input buffer is only allocated for
  mono channel. Repurpose resampler_buffer for both conversion and
  resampling.

Change-Id: I5a683148317e4fabc1c40b308472f698a8429c6b
1 file changed