qcacld-3.0: Add vendor attribute to optimize roam full scan

User can include/exclude the frequencies in roam full scan that
were already scanned by the previous partial scan, using the new
vendor attribute introduced as part of roam vendor command.
Host sends the configured value to firmware.
As per current implementation of roam scan, if there are no APs
found during partial scan, immediately a full scan will be
initiated as a fallback. This includes all channels that were
already scanned as part of partial scan.
This attribute controls the optimization, to exclude all channels
which are already scanned as part of partial scan.

Change-Id: Icd6381b4daadcfe32dabda131ae92e2e32f07f1d
CRs-Fixed: 3343657