Use CaptureConfig to share state between cores.

Remove awful FIFO_HACK.
TODO: Lots of repeated code...
TODO: Capture thread is signalled too frequently.

firmware/baseband/proc_capture.hpp

@@ -61,6 +61,8 @@ private:
 	SpectrumCollector channel_spectrum;
 	size_t spectrum_interval_samples = 0;
 	size_t spectrum_samples = 0;
+
+	void capture_config(const CaptureConfigMessage& message);
 };
 
 #endif/*__PROC_CAPTURE_HPP__*/