removed n_frames_received as it's not used

dap/accumulator.py

@@ -24,15 +24,12 @@ def accumulate(accumulator_host, accumulator_port):
 
     output = FileHandler()
 
-    n_frames_received = 0
-
     while True:
         if not zmq_socks.has_data():
             output.flush() # may be too intensive
             continue
 
         results = zmq_socks.get_data()
-        n_frames_received += 1
 
         detector = results.get("detector_name", "")
         pulse_id = results.get("pulse_id", 0)