WNM: Fetch scan results before checking transition candidates

WNM: Fetch scan results before checking transition candidates

On receiving a WNM BSS Transition Management Request frame with a
candidate list, fetch the latest scan results from the kernel to see if
there are any recent scan results for the candidates and initiate a
connection if found. This helps to avoid triggering a new scan in cases
where a scan initiated by something else (e.g., an internal beacon
measurement report functionality in a driver) has processed Beacon or
Probe Response frames without wpa_supplicant having received a
notification of such an update yet.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>