qcacld-3.0: Refine the extscan get cached results logic

Make the following updates to the extscan get cached results 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: I4144aa4cdb9c6d3ddaae30eedaec3096abf95857
CRs-Fixed: 2329405
7 files changed