switch debugfs to umode_t

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/drivers/net/wireless/libertas/debugfs.c b/drivers/net/wireless/libertas/debugfs.c
index d8d8f0d..c192671 100644
--- a/drivers/net/wireless/libertas/debugfs.c
+++ b/drivers/net/wireless/libertas/debugfs.c
@@ -704,7 +704,7 @@
 
 struct lbs_debugfs_files {
 	const char *name;
-	int perm;
+	umode_t perm;
 	struct file_operations fops;
 };