adjust arm_math.h include per dep change

the audio lib (as well as teensy core) now use the dsp lib as part of
the cmsis package

include/audio/AudioTuner.h

 
 #include <core/core_pins.h>
 #include <core/AudioStream.h>
-#include <core/arm_math.h>
+#include <arm_math.h>
 /***********************************************************************
  *              Safe to adjust these values below                      *
  *                                                                     *

src/AudioTuner.cpp

  */
 
 #include <audio/utility/dspinst.h>
-#include <core/arm_math.h>
+#include <arm_math.h>
 #include <core/Arduino.h>
 #include "audio/AudioTuner.h"