Further template BlockDecimator by element type, use for audio buffer.

Appropriating for use as a buffer accumulator that will save up enough audio samples to put into an audio DMA buffer.

firmware/baseband/proc_nfm_audio.hpp

@@ -58,8 +58,6 @@ private:
 	uint32_t channel_filter_pass_f = 0;
 	uint32_t channel_filter_stop_f = 0;
 
-	BlockDecimator<32> channel_block_buffer { post_channel_decimation_factor };	
-
 	dsp::demodulate::FM demod;
 
 	AudioOutput audio_output;