qcacmn: Tx desc counter changes

Add following Tx desc counter changes:
1. Initialize tx_desc allocated counter
2. Initialize tx desc free counter
3. Use per pool tx desc counter num_allocated to populate desc_in_use
   counter

Change-Id: I4d80d0acfbbdd32a9f7d66e938e0a0f4e2cd7048
CRs-Fixed: 2239623
3 files changed