Call directly into scheduler from VNF, start immediately

The previous designs seems to do:

    loop {
      poll_ind_queue()
      if (msg)
        scheduler;

      pselect() on messages;
      handle_message {
        if slot_ind
          put_ind_queue()
      }
    }

So basically, we artificially put a queue for slot indications in the
middle, but still handle it in the same thread(!). This for some reason
results in a big slow down if the PNF runs faster.

Now, we just do pselect(), waiting for messages. We handle the slot
indication immediately (the schedule should take some microseconds),
then return to pselect().

nfapi/open-nFAPI/vnf/public_inc/nfapi_vnf_interface.h

@@ -901,7 +901,6 @@ void nfapi_vnf_p7_config_destory(nfapi_vnf_p7_config_t* config);
  * This function is blocking and will not return until the nfapi_vnf_p7_stop
  * function is called. 
  */
-extern queue_t gnb_slot_ind_queue;
 int nfapi_vnf_p7_start(nfapi_vnf_p7_config_t* config);
 int nfapi_nr_vnf_p7_start(nfapi_vnf_p7_config_t* config);