Changed from statvv to statvlun for lun metrics

Changed the metrics for volumes to statvlun, this shows the lun metrics
(front end) as opposed to the backend volume metrics.  This is more
helpful in diagnosing performance as seen by the host.

hp_3par/python_modules/hp3par.py

@@ -52,7 +52,7 @@ def run_ssh_thread(ip,user,passwd,cmd):
 
 def get_vol_perf_stats(ip, user, passwd):
 
-    cmd = 'statvv -iter 1 -rw'
+    cmd = 'statvlun -rw -vvsum -iter 1'
     line_list = run_ssh_thread(ip, user, passwd, cmd)
     vol_perf_stats = []
     line_num = 0