audio/audio.c: remove trailing newline in error_setg

error_setg() appends newline to the formatted message.
Fixes: cb94ff5f80c5 ("audio: propagate Error * out of audio_init")

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

audio/audio.c

@@ -1744,7 +1744,7 @@ static AudioState *audio_init(Audiodev *dev, Error **errp)
         if (driver) {
             done = !audio_driver_init(s, driver, dev, errp);
         } else {
-            error_setg(errp, "Unknown audio driver `%s'\n", drvname);
+            error_setg(errp, "Unknown audio driver `%s'", drvname);
         }
         if (!done) {
             goto out;