vty/command: add CMD_ATTR_HIDDEN to CMD_ATTR_PUBLIC_MASK

Otherwise in the expert mode, hidden commands do not get the
associated attribute printed to the XML VTY reference.

Change-Id: I8ded973031beb6d8c7ad55f06641c9651b1d9e71
Related: OS#4910
diff --git a/src/vty/command.c b/src/vty/command.c
index b83522f..7ea1971 100644
--- a/src/vty/command.c
+++ b/src/vty/command.c
@@ -633,7 +633,7 @@
 
 /* Public attributes (to be printed in the VTY / XML reference) */
 #define CMD_ATTR_PUBLIC_MASK \
-	(CMD_ATTR_IMMEDIATE | CMD_ATTR_NODE_EXIT)
+	(CMD_ATTR_HIDDEN | CMD_ATTR_IMMEDIATE | CMD_ATTR_NODE_EXIT)
 
 /* Get a flag character for a global VTY command attribute */
 static char cmd_attr_get_flag(unsigned int attr)