Fix availableNodes behavior when dealing with submodules

Before this, nodes that are part of a submodule would get returned with
the name of the submodule. However, libyang requires this type of nodes
to be prefixed with the main module.

Change-Id: I6654f0efba0f0ffffd805e7718809067bf88c5c5
diff --git a/src/yang_schema.cpp b/src/yang_schema.cpp
index b243fd2..96fc744 100644
--- a/src/yang_schema.cpp
+++ b/src/yang_schema.cpp
@@ -352,7 +352,7 @@
         } else {
             ModuleNodePair toInsert;
             if (topLevelModule.empty() || topLevelModule != node->module()->name()) {
-                toInsert.first = node->module()->name();
+                toInsert.first = node->module()->type() == 0 ? node->module()->name() : libyang::Submodule(node->module()).belongsto()->name();
             }
             toInsert.second = node->name();
             res.insert(toInsert);