ALSA: Add missing KERN_* prefix to printk in sound/drivers

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/drivers/opl3/opl3_synth.c b/sound/drivers/opl3/opl3_synth.c
index 962bb9c..6d57b64 100644
--- a/sound/drivers/opl3/opl3_synth.c
+++ b/sound/drivers/opl3/opl3_synth.c
@@ -168,7 +168,7 @@
 
 #ifdef CONFIG_SND_DEBUG
 	default:
-		snd_printk("unknown IOCTL: 0x%x\n", cmd);
+		snd_printk(KERN_WARNING "unknown IOCTL: 0x%x\n", cmd);
 #endif
 	}
 	return -ENOTTY;