Remove useless check in lyNodesToTree

This is already checked before creating the vector of nodes, so no
reason to check again.

Change-Id: I07091df4be50371b6ba52e8d510256f80a2d6c6c
diff --git a/src/libyang_utils.cpp b/src/libyang_utils.cpp
index 15b1b06..b4d584f 100644
--- a/src/libyang_utils.cpp
+++ b/src/libyang_utils.cpp
@@ -55,8 +55,6 @@
     };
 
     for (const auto& it : items) {
-        if (!it)
-            continue;
         if (it->schema()->nodetype() == LYS_CONTAINER) {
             if (libyang::Schema_Node_Container{it->schema()}.presence()) {
                 // The fact that the container is included in the data tree