Fix NetconfAccess::deletePresenceContainer

This method had the same problem as deleteListInstance.

Bug: https://tree.taiga.io/project/jktjkt-netconf-cli/issue/153
Change-Id: I84d6c3323a69156c54c1159b153cdce8a22941c7
diff --git a/src/netconf_access.cpp b/src/netconf_access.cpp
index 4da25e9..777e94e 100644
--- a/src/netconf_access.cpp
+++ b/src/netconf_access.cpp
@@ -95,7 +95,8 @@
 void NetconfAccess::deletePresenceContainer(const std::string& path)
 {
     auto node = m_schema->dataNodeFromPath(path);
-    node->insert_attr(m_schema->getYangModule("ietf-netconf"), "operation", "delete");
+    auto container = *(node->find_path(path.c_str())->data().begin());
+    container->insert_attr(m_schema->getYangModule("ietf-netconf"), "operation", "delete");
     doEditFromDataNode(node);
 }