MXS-1929: Use correct variable

The service capabilities were not set for filters as the name overlapped
with a local variable. The variable name was fixed but the actual use of
it was not.

server/core/service.cc

@@ -1094,7 +1094,7 @@ bool Service::set_filters(const std::vector<std::string>& filters)
     {
         UniqueLock guard(lock);
         m_filters = flist;
-        capabilities |= capabilities;
+        capabilities |= my_capabilities;
         guard.unlock();
 
         // Broadcast a message to other workers to update their filter lists