wpa_supplicant: Handle EVENT_SCAN_RESULTS when an interface is disabled

wpa_supplicant: Handle EVENT_SCAN_RESULTS when an interface is disabled

An interface can be disabled while it has an ongoing scan request.
In such a case, when the scan results notification is received,
it was being ignored (as the interface is already disabled) so the
scan state was not cleared. This can cause undetermined behavior
for the next scan request.

To handle this, clear the scan state when EVENT_SCAN_RESULTS is
received and the interface is disabled.

Signed-off-by: Ilan Peer <ilan.peer@intel.com>