[ALSA] aoa - fix compile warning

Set a proper error code in the error path of i2sbus_attach_codec().
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

sound/aoa/soundbus/i2sbus/i2sbus-pcm.c

@@ -996,6 +996,7 @@ i2sbus_attach_codec(struct soundbus_dev *dev, struct snd_card *card,
 		if (dev->pcm->card != card) {
 			printk(KERN_ERR
 			       "Can't attach same bus to different cards!\n");
+			err = -EINVAL;
 			goto out_put_ci_module;
 		}
 		err = snd_pcm_new_stream(dev->pcm, SNDRV_PCM_STREAM_CAPTURE, 1);