schema BUGFIX do not cast extension instance to lysc_node

lysc_update_path() needs only the parent's module, so it is not
necessary to provide the parent node (lysc_node), the function only
needs the module from the parent structure whatever it is (possibly
an extension instance).
diff --git a/src/plugins_exts.h b/src/plugins_exts.h
index 9ad46a2..bad8eb2 100644
--- a/src/plugins_exts.h
+++ b/src/plugins_exts.h
@@ -164,11 +164,11 @@
  * @brief Update path in the compile context, which is used for logging where the compilation failed.
  *
  * @param[in] ctx Compile context with the path.
- * @param[in] parent Parent of the current node to check difference with the currently processed module (taken from @p ctx).
+ * @param[in] parent_module Module of the current node's parent to check difference with the currently processed module (taken from @p ctx).
  * @param[in] name Name of the node to update path with. If NULL, the last segment is removed. If the format is `{keyword}`, the following
  * call updates the segment to the form `{keyword='name'}` (to remove this compound segment, 2 calls with NULL @p name must be used).
  */
-void lysc_update_path(struct lysc_ctx *ctx, struct lysc_node *parent, const char *name);
+void lysc_update_path(struct lysc_ctx *ctx, struct lys_module *parent_module, const char *name);
 
 /** @} extensionscompile */