Failed default audio devices were removed from the list but not freed,
and that made LeakSanitizer sad. Free default audio devices as they are
consumed.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Acked-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-ID: <20231120112804.9736-1-akihiko.odaki@daynix.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>