cfg80211: Add support to sched scan to report better BSSs

Enhance sched scan to support option of finding a better BSS while in
connected state. Firmware scans the medium and reports when it finds a
known BSS which has better RSSI than the current connected BSS. New
attributes to specify the relative RSSI (compared to the current BSS)
are added to the sched scan to implement this.

Signed-off-by: vamsi krishna <vamsin@qti.qualcomm.com>
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Git-commit: bf95ecdba93b98d27ac219e79f773f2074b4ca47
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next.git


CRs-Fixed: 1112378
Change-Id: I0e3cf69ff6e0a73e23080a2d1e8ab9f51bcaba96
Signed-off-by: Vidyullatha Kanchanapally <vidyullatha@codeaurora.org>