switch debugfs to umode_t

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/kernel/relay.c b/kernel/relay.c
index 226fade..4335e1d 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -302,7 +302,7 @@
  */
 static struct dentry *create_buf_file_default_callback(const char *filename,
 						       struct dentry *parent,
-						       int mode,
+						       umode_t mode,
 						       struct rchan_buf *buf,
 						       int *is_global)
 {