schema mount UPDATE validate only present data

Do not add default nodes from all the modules
in the context.
diff --git a/src/plugins_exts/schema_mount.c b/src/plugins_exts/schema_mount.c
index 12bce15..224caec 100644
--- a/src/plugins_exts/schema_mount.c
+++ b/src/plugins_exts/schema_mount.c
@@ -954,8 +954,8 @@
     old_log_opts = ly_log_options(LY_LOSTORE_LAST);
 
     if (data_type == LYD_TYPE_DATA_YANG) {
-        /* validate all the data */
-        ret = lyd_validate_all(&sibling, NULL, val_opts, diff ? &ext_diff : NULL);
+        /* validate all the modules with data */
+        ret = lyd_validate_all(&sibling, NULL, val_opts | LYD_VALIDATE_PRESENT, diff ? &ext_diff : NULL);
     } else {
         /* validate the operation */
         ret = lyd_validate_op(op_tree, dep_tree, data_type, diff ? &ext_diff : NULL);