ALSA: pcm: Replace sprintf() with sysfs_emit()

For sysfs outputs, it's safer to use a new helper, sysfs_emit(),
instead of the raw sprintf() & co.  This patch replaces such a
sprintf() call straightforwardly with the new helper.

Link: https://lore.kernel.org/r/20220801165639.26030-6-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/pcm.c

@@ -1031,7 +1031,7 @@ static ssize_t pcm_class_show(struct device *dev,
 		str = "none";
 	else
 		str = strs[pcm->dev_class];
-	return sprintf(buf, "%s\n", str);
+	return sysfs_emit(buf, "%s\n", str);
 }
 
 static DEVICE_ATTR_RO(pcm_class);