data treee CHANGE lyd_validate variable argument now mandatory

It caused too much errors and SEGFAULTS.
diff --git a/src/context.c b/src/context.c
index 2b3bb67..0c7e405 100644
--- a/src/context.c
+++ b/src/context.c
@@ -629,7 +629,7 @@
         return NULL;
     }
 
-    if (lyd_validate(&root, LYD_OPT_NOSIBLINGS)) {
+    if (lyd_validate(&root, LYD_OPT_NOSIBLINGS, NULL)) {
         lyd_free(root);
         return NULL;
     }