qcacld-3.0: Use minimal filter for roam candidate selection

Roam invoke is triggered from userspace using bssid and channel
of the target AP. Therefore, use only the bssid and channel
specified by the userspace to retrieve the roam candidate.

Change-Id: I61d156cdd19925ba83ccf49723ed7b8d49eea3d1
CRs-Fixed: 3295815