Fix issue with xpath query

A "malformed-message" error is returned if an xpath query of the type
"/oc-sys:system/processes/process/state/name"
is made, where the xpath consists of a filter to match on the
leaf-nodes ("name") associated with multiple list entries("process").
This is because no matching apteryx-xml schema is found for this
type of XPATH query.
The proposed change fixes this issue.

schema.c

@@ -2625,8 +2625,6 @@ _sch_path_to_gnode (sch_instance * instance, sch_node ** rschema, sch_node ** vs
     char *name = NULL;
     char *last_good_schema_name = NULL;
     sch_node *last_good_schema = NULL;
-    _Atomic static sch_node *last_valid_schema = NULL;
-
 
     if (path && path[0] == '/')
     {