audio/dbus: remove unused AUDIO_CAP macro

The DBus audio backend already uses error_report() for error logging.
Remove the unused AUDIO_CAP macro which was left over from the old
logging infrastructure.

Reviewed-by: Mark Cave-Ayland <mark.caveayland@nutanix.com>
Reviewed-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

audio/dbusaudio.c

@@ -36,7 +36,6 @@
 #include "ui/dbus-display.h"
 #include "ui/dbus-display1.h"
 
-#define AUDIO_CAP "dbus"
 #include "qemu/audio.h"
 #include "audio_int.h"
 #include "trace.h"