Description of problem:
Current autoscale logic of poller thread is not correct for brick_mux environment
Version-Release number of selected component (if applicable):


How reproducible:
Always
Steps to Reproduce:
1) Setup a 3x3 volume 
2) Enable brick_multiplex
3) Set server.event-threads to 4 for a volume
4) Check poller threads for the brick
   ps -T -p `pgrep glusterfsd` | grep poll | wc -l 
   Ideally, the count of poller thread should be equal to 12(3 bricks * 4) but 
   it is showing total poller threads are 7

Actual results:


Expected results:


Additional info: