NetApp fix free space as zero during 1st vol stats update

NetApp clustered ontap drivers report space as zero
till first 60 seconds of driver start. This is causing
discomfort for some performance sensitive deployements.
This was due to async nature of the NetApp stats collection job.
Job is changed to sync at driver start to improve customer
experience.

Change-Id: I7d5cbf590897a0d328ece3a60516c92c0ad0ee7f
Closes-bug: #1253660
Merge "NetApp fix free space as zero during 1st vol stats update"