qcacld-3.0: Refine the extscan set epno logic

Make the following updates to the extscan set epno logic:
1) Exclusively use the Unified WMI data structures.
2) Refactor the vendor command processing to improve code
   maintainability.

Change-Id: I8179fd9b9acced01956232f113d656e0137231b5
CRs-Fixed: 2333537
7 files changed