ocstack: handler check

Check ehResponseHandler in serverRequest before call

Change-Id: I575ca777bbe13f50c15ff5fb9c58cb5730eee584
Signed-off-by: Oleksandr Dmytrenko <o.dmytrenko@samsung.com>

resource/csdk/stack/src/ocstack.c

@@ -5231,7 +5231,7 @@ OCStackResult OC_CALL OCDoResponse(OCEntityHandlerResponse *ehResponse)
     // Normal response
     // Get pointer to request info
     serverRequest = (OCServerRequest *)ehResponse->requestHandle;
-    if(serverRequest)
+    if(serverRequest && serverRequest->ehResponseHandler)
     {
         // response handler in ocserverrequest.c. Usually HandleSingleResponse.
         result = serverRequest->ehResponseHandler(ehResponse);