- both rpciod_up and rpciod_down do a gratious inc/dec of the
   use count - but we can't ever be inside those function unless
   it's called from an other module -> totally useless
 - rpciod() (the kernel thread) also bumps the refcount when starting
   and decrements it when exiting.  but as a different module must
   initiate this using rpciod_up/rpciod_down this is again not needed.
   (except when a module does rpciod_up without a matching rpciod_down -
   but that a big bug anyway and we don't need to partially handle that
   using module refcounts).