schema mount UPDATE support for creating nested data

Not just parsing it directly.
diff --git a/src/plugins_exts/yangdata.c b/src/plugins_exts/yangdata.c
index 55a03e3..b2e6f62 100644
--- a/src/plugins_exts/yangdata.c
+++ b/src/plugins_exts/yangdata.c
@@ -174,7 +174,7 @@
         .plugin.compile = &yangdata_compile,
         .plugin.sprinter = &yangdata_schema_printer,
         .plugin.free = yangdata_free,
-        .plugin.parse = NULL,
+        .plugin.snode = NULL,
         .plugin.validate = NULL
     },
     {0}     /* terminating zeroed record */