message: AudioSwitch: simplify
diff: #include "AudioSwitch_F32.h"
  void AudioSwitch4_F32::update(void) {
  - audio_block_f32_t *in, *out=NULL;
  + audio_block_f32_t *out=NULL;
  - out = receiveWritable_f32(0);
  + out = receiveReadOnly_f32(0);
  if (!out) return;
  AudioStream_F32::transmit(out,outputChannel); //just output to the one channel
  