In BE architecture, HW provides basic vdev stats support for upto
48 vdevs. For each vdev, there is vdev_stats_id which represents the
id of this vdev on HW. This vdev_stats_id is assigned by host and
is conveyed to HW at the time of REO TID Queue setup for the peer.
Add logic for allocation and deallocation of vdev_stats_id and
convey this id to HW.
Change-Id: If5611bf54d057ccf71c6444b5c79a26eb28df87e
CRs-Fixed: 3067843
6c7fcf1d61