mac80211: disallow seeks in minstrel debug code

No need for seek here, so let's just use nonseekable_open.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

net/mac80211/rc80211_minstrel_ht_debugfs.c

@@ -90,7 +90,7 @@ minstrel_ht_stats_open(struct inode *inode, struct file *file)
 		MINSTREL_TRUNC(mi->avg_ampdu_len * 10) % 10);
 	ms->len = p - ms->buf;
 
-	return 0;
+	return nonseekable_open(inode, file);
 }
 
 static const struct file_operations minstrel_ht_stat_fops = {
@@ -98,6 +98,7 @@ static const struct file_operations minstrel_ht_stat_fops = {
 	.open = minstrel_ht_stats_open,
 	.read = minstrel_stats_read,
 	.release = minstrel_stats_release,
+	.llseek = no_llseek,
 };
 
 void