qcacmn: fix invalid TX pool status when pool reattach

For AC based TX flow control, when try to do TX desc pool
reattach, currently even if TX desc pool avail_desc count
> BE_BK start threshold, it still mark pool status as
FLOW_POOL_ACTIVE_PAUSED.

Set correct pool status to FLOW_POOL_ACTIVE_UNPAUSED.

Change-Id: I6b675ffd71a2233ac23efbd6df2c235313f59cba
CRs-Fixed: 2687728