qcacld-3.0: Refine the extscan stop BSSID hotlist logic

Make the following updates to the extscan stop BSSID hotlist logic:
1) Exclusively use the Unified WMI data structures.
2) Update the HDD<=>SME interface to enforce the contract that SME
   must not make any assumptions about the buffers provided by HDD.

Change-Id: I01e29a96fded829c734532b021aeea1960bba641
CRs-Fixed: 2294273
7 files changed