Meira updates for bluetooth and audio (#2731)

* Add audio output

* Update Miera to fix bluetooth issues, bootloader definition.

* Added keymap with audio example

* Cleanup Meira audio code

keyboards/meira/keymaps/default/config.h

@@ -20,5 +20,15 @@
 #include "../../config.h"
 
 // place overrides here
+#define MUSIC_MASK (keycode != KC_NO)
+#ifdef AUDIO_ENABLE
+    #define STARTUP_SONG SONG(PLANCK_SOUND)
+    // #define STARTUP_SONG SONG(NO_SOUND)
+
+    #define DEFAULT_LAYER_SONGS { SONG(QWERTY_SOUND), \
+                                  SONG(COLEMAK_SOUND), \
+                                  SONG(DVORAK_SOUND) \
+                                }
+#endif
 
 #endif