Do not mark BSS entry in use if SSID has changed

Do not mark BSS entry in use if SSID has changed

This allows a BSS entry to be expired if the AP has changed its SSID
while maintaining the same BSSID and we are associated with the BSS.
Previously, the same BSSID was enough to mark all BSS entries from the
BSSID as in use regardless of the SSID and as such, they could remain in
the wpa_supplicant BSS table indefinitely as long as the association
remaining.

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