statement parser CHANGE finish statement parser for generic extension instances

To simplify review, only the statement parser is extended and it is not
integrated with the compilation proces, which is a complex change and
will be provided in a separated commit.

Fixes #1333
diff --git a/src/tree_schema_internal.h b/src/tree_schema_internal.h
index b139b69..23cf9d7 100644
--- a/src/tree_schema_internal.h
+++ b/src/tree_schema_internal.h
@@ -614,7 +614,7 @@
 /**
  * @param[in,out] exts [sized array](@ref sizedarrays) For extension instances in case of statements that do not store extension instances in their own list.
  */
-LY_ERR lysp_stmt_parse(struct lysc_ctx *ctx, const struct lysp_stmt *stmt, enum ly_stmt kw, void **result, struct lysp_ext_instance **exts);
+LY_ERR lysp_stmt_parse(struct lysc_ctx *ctx, const struct lysp_stmt *stmt, void **result, struct lysp_ext_instance **exts);
 
 /**
  * @brief Free a parsed node.