qcacld-3.0: Add vendor attribute to include 6 GHz in roam full scan

During the roam scan, if there are no desired APs found in the partial
frequency list, an immediate full scan on all the supported frequencies
is initiated as a fallback. This would include the 6 GHz PSC
frequencies by default.
This attribute allow that behavior to be modified to include PSCs only
if 6 GHz use has been detected in the environment.

Change-Id: I6dc380419f14b920737fd87cd9a487c28364563b
CRs-Fixed: 3351697
12 files changed