codal_app: Make sure volume can achieve the full CODAL range.

The CODAL setVolume() method takes a value in the range 0-255.

Fixes issue #159.

Signed-off-by: Damien George <damien@micropython.org>

Author: dpgeorge

src/codal_app/microbithal_audio.cpp

@@ -76,11 +76,7 @@ void microbit_hal_audio_select_speaker(bool enable) {
 
 // Input value has range 0-255 inclusive.
 void microbit_hal_audio_set_volume(int value) {
-    if (value >= 255) {
-        uBit.audio.setVolume(128);
-    } else {
-        uBit.audio.setVolume(value / 2);
-    }
+    uBit.audio.setVolume(value);
 }
 
 void microbit_hal_sound_synth_callback(int event) {