Clear wpa_supplicant and cfg80211 scan results at the end of hidden SSID
test cases to avoid potential issues for following test cases. For
example, ap_hs20_session_info could fail if executed immediately after
ssid_hidden due to the AP configuration change from open to RSN was not
noticed.
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>